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Nonlinear Optical Properties and Broadband Optical Power Limiting Action of Graphene Oxide Colloids
Abstract
In this work we report on the preparation of some aqueous graphene oxide (GO) dispersions and the investigation of their nonlinear optical response under visible (532 nm) and infrared (1064 nm), picosecond and nanosecond laser excitation. The GO colloids were prepared under specific and well-defined conditions resulting in finely dispersed heavily oxidized large GO sheets. In all cases, GO colloids were found to present large nonlinear absorption and negligible nonlinear refraction. The physical mechanisms responsible for their nonlinear optical response are discussed. In addition, the so-prepared GO dispersions were found to exhibit large broadband optical power limiting action for both pulse durations, comparable to that of C60 for visible laser pulses and much superior for infrared ones.
... So far, various research groups have demonstrated the broadband OL of various graphene-based nanostructures and have performed significant efforts toward the understanding of the physical mechanisms of their OL response. 24,25 In these studies, different operating mechanisms have been evoked to explain the OL action, e.g., two-or multiphoton absorption (TPA/MPA), excited-state absorption (ESA), induced thermal scattering (ITS), and thermal lensing. Furthermore, other studies have shown that chemical modification and heteroatom doping can significantly enhance the optical limiting performance of graphene derivatives. ...
... 5,6 In this study, it was demonstrated that the rational engineering of the defects of single-layered GO through chemical reduction and substitutional doping with N and/or B atoms can drastically enhance the broad-band OL performance of GO, resulting in extremely low OL on values, even though GO has been reported to exhibit very weak or negligible OL at NIR wavelengths. 25 It is noteworthy that among various potential heteroatom dopants, nitrogen has stimulated considerable interest, as it can be exploited for the formation of efficient charge transfer systems, thus leading to significant enhancement of the nonlinear optical (NLO) properties, as has been recently shown for the case of octylamine-modified fluorographene. 22 Motivated by these ideas, in the present work, the OL performance of three recently prepared N-doped graphenes, namely, nitrogen-doped graphene (NG), nitrogen-doped graphene acid (NGA, i.e., NG treated with 65% nitric acid), and nitrogen-doped graphene acid dots (NGA-D, i.e., hydrothermally treated NGA) is studied for a broad spectral range extending from 355 to 1850 nm by employing 4 ns laser radiations. ...
... According to the literature, the optical limiting of the oxidized graphene derivatives can be attributed to different physical mechanisms, including induced thermal scattering (ITS), thermal effects, two-and/or multiphoton (TPA/MPA) processes, and excited-state absorption (ESA). 24,25,43 For the range of incident laser energies employed here, the observed ITS signal was very weak and isotropic, suggesting a rather negligible contribution to the OL performance (see the Supporting Information). In addition, to avoid the manifestation of cumulative thermal effects (arising from microplasma and/or bubbles creation at the interface of the graphene sheet with the solvent), the laser repetition rate was set at 1 Hz. ...
The present work reports on the exceptional optical limiting performance of some recently synthesized nitrogen-doped graphene derivatives (NGs) by substitutional heteroatom doping. In particular, the optical limiting performance of NGs having different nitrogen contents and some NG-based quantum dots is investigated in a broad-band spectral range, from 355 to 1850 nm, using 4 ns laser pulses. The obtained results show that the present N-doped graphene derivatives exhibit very efficient broad-band optical limiting performance, attaining record low values of optical limiting onset (OLon), in particular for NIR wavelengths, significantly lower than those of other previously studied graphene derivatives and other families of benchmark materials for optical limiting. The present results demonstrate that tuning the N-doping of graphene acid is a very powerful and efficient strategy for the enhancement of the OL action of graphene, rendering it the strongest currently known optical limiting material, improving dramatically its potential for various optoelectronic and photonic applications.
... Because the above liquid convection is driven by a laser's photothermal energy, a pulsed laser beam can also induce similar flow and alignment as long as its repetition frequency is greater than 10 Hz, which is satisfied by nearly all the lasers used in Z-scan and nonlinear optics [5,[11][12][13][14]16,22,25,30,31]. Moreover, the flow-induced alignment is not limited to 2D nanomaterials [21], but universal to low-dimensional nanomaterials with large geometric anisotropy, such as one-dimensional (1D) carbon nanotubes [43] or nanowires [44]. ...
... Since most nonlinear optical studies of 2D materials suspended in solution do not consider the effect of fluid convection and the induced alignment, it is not accurate to simply ascribe the observed nonlinear-like transmissions to their intrinsic nonlinear property, no matter whether the experiments are performed with femtosecond [12][13][14], picosecond [9,12,22,31], nanosecond [5,[8][9][10][11][12][15][16][17][23][24][25][26]30,31], or CW lasers [18][19][20][27][28][29]32], and no matter whether the nanomaterials are 1D carbon nanotubes (CNTs) [10,17,23,27,28], graphene [5,[9][10][11]15,26], graphene oxide [8][9][10]12,18,26,31,32], transition metal dichalcogenides (TMDCs) [16,22,24] or black phosphor [13,14,25,30]. For example, as the most common experimental configuration, many observed nonlinear-like Z-scan curves, SA-like enhanced transmission [13,14,22,25,29,30], OL-like reduced transmission [15,17,18,[20][21][22][23][24][26][27][28], or the transition from SA to OL [8,9,12,16,24,30,31], The laser is focused into suspension, and then the energy of the incident laser is increased gradually. ...
... Since most nonlinear optical studies of 2D materials suspended in solution do not consider the effect of fluid convection and the induced alignment, it is not accurate to simply ascribe the observed nonlinear-like transmissions to their intrinsic nonlinear property, no matter whether the experiments are performed with femtosecond [12][13][14], picosecond [9,12,22,31], nanosecond [5,[8][9][10][11][12][15][16][17][23][24][25][26]30,31], or CW lasers [18][19][20][27][28][29]32], and no matter whether the nanomaterials are 1D carbon nanotubes (CNTs) [10,17,23,27,28], graphene [5,[9][10][11]15,26], graphene oxide [8][9][10]12,18,26,31,32], transition metal dichalcogenides (TMDCs) [16,22,24] or black phosphor [13,14,25,30]. For example, as the most common experimental configuration, many observed nonlinear-like Z-scan curves, SA-like enhanced transmission [13,14,22,25,29,30], OL-like reduced transmission [15,17,18,[20][21][22][23][24][26][27][28], or the transition from SA to OL [8,9,12,16,24,30,31], The laser is focused into suspension, and then the energy of the incident laser is increased gradually. ...
Nonlinear optical property of atomically thin materials suspended in liquid has attracted a lot of attention recently due to the rapid development of liquid exfoliation methods. Here we report laser-induced dynamic orientational alignment and nonlinear-like optical response of the suspensions as a result of their intrinsic anisotropic properties and thermal convection of solvents. Graphene and graphene oxide suspensions are used as examples, and the transition to ordered states from initial optically isotropic suspensions is revealed by birefringence imaging. Computational fluid dynamics is performed to simulate the velocity evolution of convection flow and understand alignment-induced birefringence patterns. The optical transmission of these suspensions exhibits nonlinear-like saturable or reverse saturable absorptions in Z-scan measurements with both nanosecond and continuous-wave lasers. Our findings not only demonstrate a non-contact controlling of macroscopic orientation and collective optical properties of nanomaterial suspensions by laser but also pave the way for further explorations of optical properties and novel device applications of low-dimensional nanomaterials.
... So far, many organic and inorganic materials have been proven to have good nonlinear optical limiting effects, such as fullerenes [6], carbon nanotubes [7], and phthalocyanine [8]. Since Wang et al. published the first paper about the nonlinear optical limiting effect of graphene [9], many researchers studied the optical limiting properties of graphene and graphene derivatives, such as large-area graphene layers [10], graphene oxide [11][12][13], a graphene oxide-phthalocyanine hybrid [14,15], and graphene dispersion [16]. Among them, the maximum laser transmittance without an optical limiting effect (linear transmittance, T 0 ) and the minimum laser transmittance with a nonlinear optical limiting effect (T min ) of graphene dispersion in N,N-dimethylacetamide at the wavelength of 1064 nm are, respectively, 78.9% and 55.2% [9], the T 0 and T min of graphene oxide dispersion in aqueous at 1064 nm are, respectively, 92% and 58% [13], and the T 0 and T min of graphene dispersion in ethanol at 532 nm are, respectively, 60% and 20% [16]. ...
... Since Wang et al. published the first paper about the nonlinear optical limiting effect of graphene [9], many researchers studied the optical limiting properties of graphene and graphene derivatives, such as large-area graphene layers [10], graphene oxide [11][12][13], a graphene oxide-phthalocyanine hybrid [14,15], and graphene dispersion [16]. Among them, the maximum laser transmittance without an optical limiting effect (linear transmittance, T 0 ) and the minimum laser transmittance with a nonlinear optical limiting effect (T min ) of graphene dispersion in N,N-dimethylacetamide at the wavelength of 1064 nm are, respectively, 78.9% and 55.2% [9], the T 0 and T min of graphene oxide dispersion in aqueous at 1064 nm are, respectively, 92% and 58% [13], and the T 0 and T min of graphene dispersion in ethanol at 532 nm are, respectively, 60% and 20% [16]. Many experiments have proved that graphene and its derivatives have good optical limiting performance, and it is significant to find more appropriate solvents to improve its nonlinear optical limiting performance. ...
... To the best of our knowledge, it is the first time to study the optical limiting effects of graphene in ethanol and acetone dispersion at 1064 nm. In our experiment, the T 0 and T min of graphene dispersion in acetone at 1064 nm are, respectively, 77.8% and 20.3%, which is better than that of the graphene in other organic solvents [9,13,16]. The graphene dispersion we used also has advantages of chemical stability and simple manufacturing process. ...
We study the nonlinear optical limiting effect of graphene dispersions in ethanol and acetone at a wavelength of 1064 nm. The nonlinear optical limiting effect of graphene dispersion under three different linear transmittances (about 70%, 80%, and 90%), two different thicknesses (1 and 3 cm), and two different solvents (ethanol and acetone) are measured. The influences of concentration, thickness, and solvent on the nonlinear optical limiting effect of the graphene dispersion are analyzed. The experimental results show that the concentration and solution thicknesses have great influence on the optical limiting ability of graphene dispersions. The graphene dispersions with ethanol and acetone as solvents can be used to achieve excellent nonlinear optical limiting effects. The optical limiting ability of the graphene dispersion in acetone is better than that of the graphene dispersion in ethanol.
... 18,19 Among the various two-dimensional (2D) graphene counterparts, graphene oxide (GO) represents a key functionalized analogue 20 combining cost-effective and facile manufacturing methods 21 while, inter alia, it is characterized by excellent optoelectronic features due to its significant nonlinear optical (NLO) response. 22,23 Compared to graphene, GO exhibits much more efficient dispersibility, and therefore easier handling and processability, since it does not easily agglomerate in aqueous and/or other common organic solvents because of the several oxygen-containing functional groups (phenolic, carboxyl, and epoxide groups) usually attached on the basal plane or at the edges of the sheet. 20 Because of this, GO is regarded as an even more attractive material as it is generally considered as an efficient platform for the preparation of functionalized graphene-based materials as well as opens up exciting possibilities and prospects for the development of advanced devices after its chemical reduction. ...
... It should be mentioned that RSA was observed for all concentration's dispersions and even for the lowest laser intensities used (where a transition from SA to RSA is sometimes observed in graphenes). 23 In principle, such a behavior emanates from the operating physical mechanisms underlying the NLO response under nanosecond laser excitation. Actually, the RSA response can be ascribed to different physical processes, such as two-or multiphoton absorption or excited state absorption, that can be effective during the nanosecond excitation as it has been reported and discussed elsewhere. ...
... However, the presence of higher order processes (e.g., 3PA and 5PA) results, in general, in narrower OA Z-scan recordings than those due to 2PA processes as it has been discussed elsewhere. 23,43 Because in the present work the OA Z-scan recordings were found rather broad, the presence of higher order process can be excluded, suggesting and 2PA processes can be assumed as being the most probably occurring under the current experimental conditions. ...
... 17 In contrast, graphene oxide (GO) and GO linked with metal/organic complexes have both been reported to exhibit strong OL at much lower fluencies than graphene, both in the nanosecond and picosecond regimes, owing to reverse saturable absorption (RSA) or RSA/two-photon absorption (TPA) mechanisms. 18 In another work, regarding reduced graphene oxide films having a different degree of reduction, the OL performance has been shown to depend on the ratio of the sp 2 /sp 3 domains; the greater this ratio, the better the OL achieved. 22 Similarly, in a recent report from our group regarding the nonlinear absorption of some graphene oxide dispersions, it was shown that decreasing the degree of oxidation gives rise to stronger RSA behavior, suggesting that the extent of π-conjugation, as quantified by the amount of sp 2 species arranged in nanodomains, plays a crucial role in GO's broadband NLO absorption under nanosecond laser excitation. ...
... This observation suggests that the NGO lattice has less structural defects than that of BGO, which is in tune with the results of the other spectroscopic analyses performed. 18,24 It should be also noted that, in general, the thermal reduction introduces more small sized sp 2 domains in BGO and NGO. The higher I D /I G ratio, in the case of BGO, indicates the presence of large amounts of small sp 2 domains, in tune with the earlier reports, 26 and hence the presence of more sp 2 −sp 3 interfaces compared to NGO. ...
... The OL on values at each irradiation wavelength were determined from the experimental transmittance data shown in Figure S1 and are also listed in Table 1. As can be seen, a continuously decreasing trend of the values of OL on is observed with the laser excitation wavelength (i.e., 18,28,29 In the present study, the contributions of the last two mechanisms have been investigated separately (see also the Supporting Information); however, they were found to be rather insignificant under the present experimental conditions. Hence, the OL exhibited by the BGO-and NGO-modified GOs should be attributed to the operation of RSA and/or TPA mechanisms. ...
Graphene derivatives and defect-engineered graphenes have attracted the interest of researchers owing to the excellent and tunable properties they exhibit. In this work the optical limiting performance of two defect-engineered boron- and nitrogen-doped reduced graphene oxides is investigated. Both graphenes are found to exhibit exceptional and broadband optical limiting action ranging from 532 to 2200 nm. Their optical limiting efficiency was found to be superior to that of all the other graphene derivatives studied to date, exhibiting a gradually decreasing optical limiting onset, reaching the record low value of ∼0.002 J cm-2 at 2200 nm. The results demonstrate the potential of engineering the defects of such reduced graphene oxides, resulting in very broadband and efficient optical limiting graphene derivatives, showing a promising method to further tailor their optical and optoelectronic properties.
... The optical limiting in carbon-based materials in particular, in graphene and in its derivatives has been extensively investigated in the last years [14][15][16][17]. The optical limiting functionality of these materials, as suspension, film or bulk, has been mainly studied for visible and near-infrared nanosecond and picosecond laser pulses (for wavelengths shorter than 1100 nm) [18][19][20][21] and, to a lesser extent, for femtosecond laser pulses (mostly at 800 nm wavelength) [22][23][24][25][26]. Very few papers have investigated the nonlinear optical absorption and optical limiting of femtosecond laser pulses in the IR-B band (range, 1.4-3 μm), which includes the wavelength of 1550 nm, important for communications [27,28]. ...
... The optical limiting in carbon-based materials, in particular, in graphene and in its derivatives, has been extensively investigated in the last years [14][15][16][17]. The optical limiting functionality of these materials, as suspension, film or bulk, has been mainly studied for visible and near-infrared nanosecond and picosecond laser pulses (for wavelengths shorter than 1100 nm) [18][19][20][21] and, to a lesser extent, for femtosecond laser pulses (mostly at 800 nm wavelength) [22][23][24][25][26]. Very few papers have investigated the nonlinear optical absorption and optical limiting of femtosecond laser pulses in the IR-B band (range, 1.4-3 µm), which includes the wavelength of 1550 nm, important for communications [27,28]. ...
... The OL trend in the silico-phosphate glassy films with rGO on the ITO-coated glass substrate is similar to that reported in isolated fullerene-rich thin films at the wavelength of 532 nm [57]. In our case, the onset of OL (defined as the point on the transmittance curve at which it starts to diverge from the linear transmittance [19]) is much lower (<0.5 mJ/cm 2 ) than the values (60-140 mJ/cm 2 , for different samples) reported in [57]. ...
The development of graphene-based materials for optical limiting functionality is an active field of research. Optical limiting for femtosecond laser pulses in the infrared-B (IR-B) (1.4–3 μm) spectral domain has been investigated to a lesser extent than that for nanosecond, picosecond and femtosecond laser pulses at wavelengths up to 1.1 μm. Novel nonlinear optical materials, glassy graphene oxide (GO)-based silico-phosphate composites, were prepared, for the first time to our knowledge, by a convenient and low cost sol-gel method, as described in the paper, using tetraethyl orthosilicate (TEOS), H3PO4 and GO/reduced GO (rGO) as precursors. The characterisation of the GO/rGO silico-phosphate composite films was performed by spectroscopy (Fourier-transform infrared (FTIR), Ultraviolet–Visible-Near Infrared (UV-VIS-NIR) and Raman) and microscopy (atomic force microscopy (AFM) and scanning electron microscope (SEM)) techniques. H3PO4 was found to reduce the rGO dispersed in the precursor’s solution with the formation of vertically agglomerated rGO sheets, uniformly distributed on the substrate surface. The capability of these novel graphene oxide-based materials for the optical limiting of femtosecond laser pulses at 1550 nm wavelength was demonstrated by intensity-scan experiments. The GO or rGO presence in the film, their concentrations, the composite films glassy matrix, and the film substrate influence the optical limiting performance of these novel materials and are discussed accordingly.
... [54]. b Values taken from ref. [55]. c Values taken from ref. [5]. ...
... Finally, the NLO properties of the present SiNSs will be compared to those of some graphene derivatives (as e.g., graphene oxide (GO), nitrogen-doped GO (N-GO), borondoped GO (B-GO) and fluorographene (CF)), which have been recently investigated under similar excitation conditions [5,55,56]. For comparison purposes, all the obtained results are summarized in Table 1. ...
The present work reports on the transient nonlinear optical (NLO) responses of two different types of 2D silicon nanosheets (SiNSs), namely hydride-terminated silicon nanosheets (SiNS–H) and 1-dodecene-functionalized silicon nanosheets (SiNS–dodecene). The main motivation of this study was to extend the knowledge regarding the NLO properties of these Si–based materials, for which very few published studies exist so far. For that purpose, the NLO responses of SiNS–H and SiNS–dodecene were investigated experimentally in the nanosecond regime at 532 and 1064 nm using the Z-scan technique, while the obtained results were compared to those of certain recently studied graphene nanosheets. SiNS–dodecene was found to exhibit the largest third-order susceptibility χ(3) values at both excitation wavelengths, most probably ascribed to the presence of point defects, indicating the importance of chemical functionalization for the efficient enhancement and tailoring of the NLO properties of these emerging 2D Si-based materials. Most importantly, the results demonstrated that the present silicon nanosheets revealed comparable and even larger NLO responses than graphene nanosheets. Undoubtedly, SiNSs could be strong competitors of graphene for applications in 2D-material-based photonics and optoelectronics.
... The oxygen group abundance in GO makes them suitable for their chemical functionalization. To enhance the NLO properties of GO, various multifunctional groups as dye molecules, organic materials, and dielectrics have been attached to fabricate reduced graphene oxide, graphene oxide colloids, and graphene hybrids, etc. [153][154][155]. Wang et al. [156] reported the fabrication of monolayers of graphene and multilayer of graphene dispersion in an organic solvent, making it to exhibit unique nonlinear optical properties and broadband OL for ns pulses. ...
... Following the same trend of CNTs, and CBS [53,54,96,97], graphene suspension also ascribed the NLS mechanism for their optical limiting effects. However, recently NLA has also emerged as an effective mechanism [150,153,155] in the optical limiting of graphene-based nanocomposites. Feng and co-workers [157] demonstrated the broadband optical limiting of a large family of graphene including graphene nanosheets, GO nanosheets, graphene nanoribbons, and GO nanoribbons for 532 nm and 1064 nm excitation wavelength ns pulses. ...
The optical limiting behavior of numerous nonlinear materials has been reviewed. Explicit examination of non-linear mechanisms such as multiphoton absorption, nonlinear absorption, nonlinear scattering and their peculiar implementation in optical devices using nonlinear materials as carbon nanotubes, fullerenes, semiconductors, graphene, and carbon black suspensions have been performed. Reflection-based optical limiters are especially emphasized for their self-protecting optical limiting over a broad transmission bandwidth. A comparative study of limiting parameters of several nonlinear materials is also included.
... Today, graphene is known as a utile optical nanomaterial due to its superior optical properties and particularly the optical nonlinear traits which have led to the various applications. These include saturable absorption, optical limiting and optical bistability as the principal mechanism of the optical switching [1][2][3][4][5][6][7]. Meanwhile, the graphene-based heterostructures are demanded for their enhanced nonlinearity [8][9]. ...
... 3 is the third order susceptibility of the nonlinear medium and x denotes the lateral coordinate of propagating direction. For the different frequencies, 3 is obtained in terms of the optical conductivity 3 for interband/intraband transitions as given in ...
In this paper, we investigate the spatial beam propagation inside a nonlinear medium with multiple graphene flakes dispersed in a dielectric media. This is done by solving the governing nonlinear equation using the common Beam Propagation Method. We consider a modified nonlinearity for the medium through our calculations. Our results show that the effect Modulational Instability(MI) occurs for the higher wavelengths/large number of dispersed graphene flakes. At THz range, our results indicate that the MI procedure will not proceed as we anticipate. Instead, a train of discrete spatial solitons will be present. Our simulation results are in good agreement with the other similar but non-parallel researches.
... In general, the highly fluorinated graphenes investigated were found exhibiting self-defocusing, in contrast to fluorographenes with low F-content, the latter exhibiting self-focusing, as it has been reported previously. [24,32] This sign alternation of the NLO refraction can be correlated with the variation of the nature of the C-F bonding varying with the F-content, leading to modification of the charge sharing of the ionic C-F bond. So, in presence of low F-content, ionic C-F bonding is favored, while at higher F-content, the "semiionic" (covalently) C-F bonding prevails. ...
... In another recent study, investigating the OL behavior of some graphene oxide colloids, having a transmittance between 50 and 70%, the OL thr value was reported to be about 0.1 J cm −2 . [32] From all of the aforementioned cases, CDEA seems to exhibit much better OL performance, having a OL thr value of only 0.045 J cm −2 . A further comparison of the OL action of the present modified fluorographene under ns laser excitation, with other 2D materials can be also done, however, it should be kept in mind that most of the 2D materials exhibit strong SA behavior (due to one-photon absorption), which can be transformed to RSA behavior, that is, a response directly related to optical limiting, at higher intensity, as a result of other mechanisms which become operational above a certain incident laser intensity, such as two-photon absorption, NLO scattering, and so on. ...
The present work reports on the broadband optical limiting performance and the enhancement of the nonlinear optical (NLO) response of a diethylamino‐modified fluorographene compared to pristine fluorographene and other modified fluorographenes. The present modified fluorographene was found exhibiting very efficient and broadband optical limiting action, for optical radiations extended from the visible (i.e., 500 nm) and up to near infrared (i.e., 1.8 μm). Its optical limiting threshold was found to be better that 0.045 J cm−2 making it a very promising material for optical limiting applications. In addition, the functionalization of fluorographene by the diethylamino ligand resulted in switching on the NLO response of fluorographene, attaining a third‐order nonlinear susceptibility χ(3) of the order of 10−9 esu under ns, visible and infrared laser excitation. The present work demonstrates the efficiency and the new horizons opened by suitable chemical functionalization of fluorographene, towards the tailoring of its nonlinear optical response and optical power limiting action, towards several applications in photonics and optoelectronics and for the preparation of materials with custom made properties. Diethylamino fluorographene is synthesized by partial nucleophilic substitution of fluorographene by lithium diethylamide LiN(C2H5)2. The functionalization of fluorographene results in switching ON its nonlinear optical response, under ns visible and infrared laser excitation. The diethylamino fluorographene exhibits efficient and broadband optical limiting action, up to 1.8 μm. The efficient tunability of the nonlinear optical properties exploiting fluorographene's chemistry is highlighted.
... Vis-UV spectra of GO have three peaks at 230, 300, and 364 nm; the strongest one appears at 236 nm and is usually due to the transition π → π* from the aromatic planer network of GO, While the peak of 300 nm shows the transition n → π* [33]. However, the peak of 364 nm represents the fine dispersion of the sheets and usually does not appear easily [34]. Fig. 1b also displays that GO absorption is increased at all wavelengths after PEGylation, which is apparent by changing the color of the GO-PEG from brown to darker. ...
Objective(s): The waves of ultrasound and laser in the presence of nanoparticles are introduced as desirable candidates for the thermal treatment of cancer due to having fewer side effects, more speed, and superior treatment efficiency. Here, 2D Graphene oxide nanoparticle is used as a thermal nano-convertor for increasing the yield of thermal cancer therapy. Materials and Methods: The temperature of GO (in 0.2 and 0.4 mg/ml concentrations) and deionized water regarding heater, bath sonicate, probe sonicate (at a power range of 2-3.5 W), and laser properties at 808 nm with continuous wave (at a power of 0-2 W) in 10 min are investigated. Based on the experimental results, the effect of laser and ultrasound radiation on the temperature is simulated using a data mining approach. Results: Experimental and simulation results show that GO nanoparticle in this form is unsuitable for converting ultrasound waves into heat. But it is a strong absorber for electromagnetic waves at 808 nm and can raise the temperature to 85 °C. The results indicate that the laser + GO enhances the mortality percentage and treatment yield of MG63 cancerous cells by up to 85%. Also, GO uptake is analyzed by fluorescent microscopic images. Conclusion: This analysis confirmed that GO is important when laser radiation is used but not when Ultrasound is employed. Also, GO is an excellent photothermal nanoparticle for localized thermal therapy of osteosarcoma cancer cells by laser at 808 nm with low side effects.
... Among the studied materials with optical limiting properties are carbon-based materials, e.g., graphene and its derivates [15,[19][20][21]23]. The OL functionality of these materials, in different forms as solutions, films, and bulk, has been mainly studied for visible and near-infrared nanosecond and picosecond laser pulses [24][25][26][27][28] and, in a smaller measure, for femtosecond laser pulses at 800 nm wavelength [29][30][31][32][33]. Very few papers have investigated the OL of femtosecond laser pulses in the IR band, which includes the wavelength of 1550 nm, an important wavelength for communications. B. N. S. Sooraj et al. reported in a recent study [34] the optical limiting of 35 ps laser pulses at 532 nm in silver, gold, and alloy clusters, investigated by Z-scan technique. ...
The high-power lasers have important implications for present and future light-based technologies; therefore, the protection measures against their high-intensity radiation are extremely important. Currently, a great deal of interest is directed towards the development of new nonlinear optical materials for passive optical limiters, which are used to protect the human eye and sensitive optical and optoelectronic devices from laser-induced damage. Biopolymers doped with natural dyes are emerging as a new class of optical materials with interesting photosensitive properties. In this paper, the optical limiting capability of deoxyribonucleic acid bio-polymer functionalized with Turmeric natural dye has been demonstrated for the first time, to the best of our knowledge. The experimental investigation of the optical limit has been done by the Intensity-scan method in the NIR spectral domain at the important telecommunication wavelength of 1550 nm, using ultrashort laser pulses (~120 fs). Several optical properties of this natural dye are presented and discussed. The values of the optical transmittance in the linear regime, the saturation intensity of the nonlinear transmittance curves, and the coefficient of the nonlinear absorption have been determined. The influence of the DNA biopolymer and natural dye concentration on the optical limiting properties of the investigated biomaterials is reported and discussed. The photostability and thermal stability of the investigated solutions have also been evaluated by monitoring the temporal decay of the normalized absorption spectra under illumination with UVA light and heating, respectively. Our results evidence the positive influence of the DNA, which embeds Turmeric natural dye, on the optical limiting functionality itself and on the photostability and thermal stability of this novel material. The performed study reveals the potential of the investigated novel biomaterial for applications in nonlinear photonics, in particular in optical limiting.
... 14 As a result, third-order optical nonlinearity has been extensively investigated in various materials, ranging from metals, 15 semimetals, 16 semiconductors from low dimension (0−2) to bulk, 17−19 organic materials, 20 and topological materials. 21 Typical examples of the materials that exhibit good third-order nonlinear optical response are graphene oxide (GO), 22 single-and multiwall carbon nanotube, 23,24 transition metal dichalcogenides, 25 amorphous chalcogenide glasses, 26 plasmonic materials, 27 and quantum dots. 17 Unfortunately, conventional materials typically exhibit weak third-order nonlinear optical responses, even under strong optical fields owing to their perturbative nature, although a strong response is crucial for applications. ...
... (e. g., graphene, graphene oxide, MoS 2 , WS 2 , MoSe 2 , WSe 2 , black phosphorous and antimonene), all studied under similar nanosecond irradiation conditions (see also Table S2). [49][50][51][52] In that respect, the OL on value of a similar transmittance (i. e.,~93 %) 1,2-dichlorobenzene fullerene-C 60 solution has been reported to be about 0.26 J/cm 2 under nanosecond 532 nm laser irradiation, [28] suggesting very similar OL performance to that of present hematene and magnetene nanoplatelets. ...
Recently, the preparation of some hematene and magnetene ultrathin non van der Waals (non‐vdW) 2D nanoplatelets was reported starting from hematite and magnetite natural iron ores. The present work reports on the determination and evaluation of the nonlinear optical response and the optical limiting (OL) action of these 2D nanoplatelets dispersed in water under ns laser excitation. The obtained results show that both hematene and magnetene exhibit strong nonlinear absorption and refraction, comparable and even larger than those of other van der Waals (vdW) 2D counterpart materials. In addition, due to their strong nonlinear absorption, both hematene and magnetene show exceptional OL performance from the UV to visible, attaining very low values of optical limiting onset (OLon), comparable and even lower than that of vdW 2D nanomaterials, such as graphene, graphene oxide, other transition metal dichalcogenides like MoS2, WS2 and MoSe2, black phosphorous and antimonene. Moreover, hematene was found to exhibit more efficient OL action than magnetene for all the excitation wavelengths studied, attributed to more efficient ligand to metal charge transfer. The present findings open new possibilities for the potential use of these non‐vdW 2D materials in photonics and optoelectronics, e. g., as optical limiters and optical switchers.
... As a result, third-order optical nonlinearity has been extensively investigated in various materials, ranging from metals 15 , semimetals 16 , semiconductors from low dimension (0-2) to bulk [17][18][19] , organic materials 20 and topological materials 21 . Examples of materials with good third-order nonlinear optical response include: graphene oxide (GO) 22 , single-and multi-wall carbon nanotube 23,24 , transition metal dichalcogenides (TMDs) 25 , amorphous chalcogenide glasses 26 , plasmonic materials 27 and quantum dots 17 . Unfortunately, conventional materials typically exhibit weak third-order nonlinear optical responses, even under intense illumination owing to its perturbative nature, while a strong response is crucial for applications 8 . ...
Nonlinear optical phenomena play a critical role in understanding microscopic light-matter interactions and have far-reaching applications across various fields, such as biosensing, quantum information, optical switching, and all-optical data processing. Most of these applications require materials with high third-order absorptive and refractive optical nonlinearities. However, most materials show weak nonlinear optical responses due to their perturbative nature and often need to be improved for practical applications. Here, we demonstrate that the charge donor-acceptor hybrid of VSe2-reduced graphene oxide (rGO) hybrid exhibits enhanced ultrafast third-order absorptive and refractive nonlinearities compared to the pristine systems, at least by one order of magnitude. Through density functional theory and Bader charge analysis, we elucidate the strong electronic coupling in the VSe2-rGO hybrid, involving the transfer of electrons from VSe2 to rGO. Steady-state and time-resolved photoluminescence (PL) measurements confirm the electronic coupling and charge transfer. Furthermore, we fabricate an ultrafast optical limiter device with better performance parameters, such as an onset threshold of 2.5 mJ cm-2 and differential transmittance of 0.42.
... FCA is expected to occur in ITO film because ITO is an n-type semiconductor with free carriers in the 5 s that absorb incident photons and excite them to a higher excited state in the conduction band (5p) shown in Fig. 9. When the number of O vacancies and donor levels increase, defect state absorption increases, improving the RSA (Liaros et al. 2013). From Fig. 9. N 0 , N D , N 1 , and N 2 denote the population densities corresponding to ground-state (S 0 ), defect state (SD), and first and second excited states. ...
The nonlinear absorption (NLA) properties of ITO thin films were performed by utilizing femtosecond (100 fs), a high-repetition rate (80 MHz), and near-infrared (NIR) (750-820 nm) laser pulses. A radio frequency (RF) magnetron sputtering system was used to prepare ITO thin films of two different thicknesses. A scanning electron microscope was used to determine the film thickness and a UV-Visible spectrophotometer was used to observe the linear optical properties of the thin films. The open aperture Z-scan technique's nonlinear absorption studies of ITO thin films exhibited a reverse saturable absorption. The NLA properties of the ITO films varied depending on ITO thickness, incident laser power, and excitation wavelength, attributed to the increasing localized defect states in the band gap. The results showed that increasing the excitation wavelength from 750 to 820 nm reduces the nonlinear absorption coefficient of the ITO thin films from 15.88 × 10 −7 to 9.43 × 10 −7 cm/W and from 6.72 × 10 −7 to 5.15 × 10 −7 cm/W at ITO thicknesses of 280 and 170 nm, respectively. In contrast to the film thickness, the nonlinear absorption coefficient was inversely proportional to the excitation laser wavelength. Additionally, the optical limiting of ITO thin films was investigated, and it was found that there is a clear correlation between optical limiting and thin film thickness.
... No data was used for the research described in the article. [12] 532 nm/190 fs 0.92 0.0036 19.0 DPDA/Toluene [12] 532 nm/5 ps 0.92 0.15 30.0 2/THF [22] 770 nm/100 fs / 0.00054 5.4 [WS 4 Cu 4 I 2 (py) 6 ]/DMF [23] 532 nm/40 ps 0.73 0.07 1.8 [24] 532 nm/32 ps 0.50 ~0.1 3.1 ...
... A good material used for NOL will allow weak light to pass through with high transmission, while blocking strong light with low transmission, and it can thus protect human eyes and optoelectronic systems from the harmful high-intensity lasers [4,5]. Large-area graphene layers [6], graphene oxide [7][8][9], graphene oxide-phthalocyanine hybrids [10,11], and graphene dispersions [12] were proven to have different optical limiting effects. As a member of the graphene family, porous graphene has a special porous structure, and it thus exhibits properties distinct from those of graphene [13]. ...
This work presents a new, to the best of our knowledge, porous graphene dispersion in ethanol that can achieve a good nonlinear optical limiting (NOL) effect at the wavelength of 1064 nm. Using the ${Z}$ Z -scan system, the nonlinear absorption coefficient of the porous graphene dispersion with a concentration of 0.01 mg/mL was measured as ${9.69} \times {{10}^{- 9}}\;{\rm cm}/{\rm W}$ 9.69 × 10 − 9 c m / W . The NOL of the porous graphene dispersions in ethanol under three different concentrations (0.01, 0.02, and 0.03 mg/mL) were measured. Among them, the 1-cm-thick porous graphene dispersion with a concentration of 0.01 mg/mL has the best optical limiting effect, in which the linear transmittance is 76.7%, and the lowest transmittance is 24.9%. By using the pump-probe technique, we detected the formation and annihilation times of the scatter when the suspension interacts with the pump light. The analysis shows that the NOL mechanisms of the novel porous graphene dispersion are mainly nonlinear scattering and nonlinear absorption.
... While more complex, the latter case provides more versatility to explore the temporal, polarization, and angular dependences of the nonlinearity as well as degenerate and non-degenerate spectral dependences. [Siegman 1962, Smirl 1975, Soileau 1983, Gu 2006, Maas 2008, Liaros 2013, Riggs 2000]. Note that the I-scan technique had previously been used before being named as such (see, for example, [Bechtel 1976, Van Stryland 1985). ...
In its 60 years of existence, the field of nonlinear optics has gained momentum especially over the past two decades thanks to major breakthroughs in material science and technology. In this article, we present a new set of data tables listing nonlinear-optical properties for different material categories as reported in the literature since 2000. The papers included in the data tables are representative experimental works on bulk materials, solvents, 0D-1D-2D materials, metamaterials, fiber waveguiding materials, on-chip waveguiding materials, hybrid waveguiding systems, and materials suitable for nonlinear optics at THz frequencies. In addition to the data tables, we also provide best practices for performing and reporting nonlinear-optical experiments. These best practices underpin the selection process that was used for including papers in the tables. While the tables indeed show strong advancements in the field over the past two decades, we encourage the nonlinear-optics community to implement the identified best practices in future works. This will allow a more adequate comparison, interpretation and use of the published parameters, and as such further stimulate the overall progress in nonlinear-optical science and applications.
... While more complex, the latter case provides more versatility to explore the temporal, polarization, and angular dependences of the nonlinearity as well as degenerate and non-degenerate spectral dependences. [Siegman 1962, Smirl 1975, Soileau 1983, Gu 2006, Maas 2008, Liaros 2013, Riggs 2000]. Note that the I-scan technique had previously been used before being named as such (see, for example, [Bechtel 1976, Van Stryland 1985). ...
In its 60 years of existence, the field of nonlinear optics has gained momentum especially over the past two decades thanks to major breakthroughs in material science and technology. In this article, we present a new set of data tables listing nonlinear-optical properties for different material categories as reported in the literature since 2000. The papers included in the data tables are representative experimental works on bulk materials, solvents, 0D-1D-2D materials, metamaterials, fiber waveguiding materials, on-chip waveguiding materials, hybrid waveguiding systems, and materials suitable for nonlinear optics at THz frequencies. In addition to the data tables, we also provide best practices for performing and reporting nonlinear-optical experiments. These best practices underpin the selection process that was used for including papers in the tables. While the tables indeed show strong advancements in the field over the past two decades, we encourage the nonlinear-optics community to implement the identified best practices in future works. This will allow a more adequate comparison, interpretation and use of the published parameters, and as such further stimulate the overall progress in nonlinear-optical science and applications.
... While more complex, the latter case provides more versatility to explore the temporal, polarization, and angular dependences of the nonlinearity as well as degenerate and non-degenerate spectral dependences. [Siegman 1962, Smirl 1975, Soileau 1983, Gu 2006, Maas 2008, Liaros 2013, Riggs 2000]. Note that the I-scan technique had previously been used before being named as such (see, for example, [Bechtel 1976, Van Stryland 1985). ...
In its 60 years of existence, the field of nonlinear optics has gained momentum especially over the past two decades thanks to major breakthroughs in material science and technology. In this article, we present a new set of data tables listing nonlinear-optical properties for different material categories as reported in the literature since 2000. The papers included in the data tables are representative experimental works on bulk materials, solvents, 0D-1D-2D materials, metamaterials, fiber waveguiding materials, on-chip waveguiding materials, hybrid waveguiding systems, and materials suitable for nonlinear optics at THz frequencies. In addition to the data tables, we also provide best practices for performing and reporting nonlinear-optical experiments. These best practices underpin the selection process that was used for including papers in the tables. While the tables indeed show strong advancements in the field over the past two decades, we encourage the nonlinear-optics community to implement the identified best practices in future works. This will allow a more adequate comparison, interpretation and use of the published parameters, and as such further stimulate the overall progress in nonlinear-optical science and applications
... Compared with graphene, GO has a large number of various oxygencontaining groups on the surface. These oxygen-containing groups give GO not only many unique nonlinear optical properties [17][18][19][20], but also great potential for fabricating composite materials [21]. Hence, the graphite oxide reduction method is generally used to prepare graphene and its composites with other materials, which could provide a way to form a complex of graphene with semiconductor quantum dots, metal nanoparticles, etc., through covalency, hydrogen bonding, or electrostatic adsorption [22]. ...
The composite of graphene and semiconductor nanoparticles has attracted increasing interest in the search for novel nonlinear optical materials. Herein, composites of reduced graphene oxide (RGO) and SnO 2 nanoparticles with different mass ratios were synthesized via a facile hydrothermal method. The structural morphology and basic physical properties of the SnO 2 /RGO composites were characterized using TEM, SEM, XRD, Raman, XPS and UV– Vis spectra, indicating that SnO 2 nanoparticles were uniformly anchored on the surface of graphene nanosheets through covalent and partial-ionic bonds. The third-order optical nonlinearities of the composites were studied for the first time by the Z-scan technique using a picosecond laser at 532 nm. It was found that the composites demonstrated saturable absorption and positive nonlinear refraction properties, and both were significantly enhanced compared with pure SnO 2 nanoparticles and RGO nanosheets, and the enhancement was tunable with the variation of SnO 2 :GO mass ratio. The maximum saturable absorption coefficient and the third-order susceptibility of the as-prepared SnO 2 /RGO composites were obtained to be -2.93Χ10 ⁻¹¹ m/W and 2.25Χ10 ⁻¹¹ esu, respectively. The maximum saturable absorption modulation depth obtained was 10% with the corresponding saturation light intensity of 0.3 GW/cm ² . Moreover, the optimised third-order susceptibility of SnO 2 /RGO was found much greater than many other materials ever studied. Several involved factors contributing to the nonlinearities were discussed. The results propose that the third-order optical nonlinearities of SnO 2 /RGO and other similarly structured composites can be potentially tuned to meet certain application requirements of nonlinear optical devices by controlling the mass ratio of semiconductor to graphene.controlling the mass ratio of semiconductor to graphene.
... Considering the quasi type-II band structure and large volume, the two-photon absorption crosssection of S2 is one order larger than that in one-dimensional CdSe QDs [24,25]. The measured third-order nonlinearity are also comparable to those measured in two-dimensional graphene [26,27], graphene oxide [28] and silicon nanosheets [29] with similar experimental condition. ...
Colloidal semiconductor nanoplatelets, a kind of one-dimensional quantum confined materials, have been widely investigated due to their remarkable excitonic effect, in which excellent two-photon absorption property has been proved. In this work, 4.5 monolayers thick CdSe nanoplatelets laterally extended with CdS were synthesized and their crown size-dependent third-order nonlinear optical properties were measured through a picosecond Z-scan method. The detailed investigation combining the time-related photoluminescence spectroscopy reveals the effective passivation of the CdSe boundary with same area size of the core could improve the quantum yield up to 85% and third-order nonlinearity. In addition, the two-photon absorption cross-section can reach up to 6.8 × 10⁶ GM due to the quasi-type Ⅱ band structure of these core/crown nanoplatelets.
... The NIR light irradiation can be useful for photothermal therapy of cancer, resulting in significant tumor ablation [92]. The excellent nonlinear optical property of GR is related to the features such as (i) nonlinear scattering, (ii) expansive π-conjugate system, (iii) two-photon absorption, and the (iv) linear dispersion relation holding for its electronic band structure [93][94][95][96][97]. The luminescent property of GR is generated by cutting GR into nanoribbons and quantum dots (QDs) or by oxygen plasma treatment [98][99][100][101]. ...
To date, tissue engineering and regenerative medicine has been substantially advanced using bioactive functional nanomaterials. Having capitalized on various safe and biocompatible advanced materials, different types of biomimetic scaffolds have been engineered and exploited as an ideal setting for the safe accommodating and delivery of the incorporated cells to the damaged/defected tissues. As a carbon-based allotrope with a single layer of atoms, graphene displays a two-dimensional nanoscale honeycomb matrix and provides a great possibility for surface functionalization. Graphene and its derivatives have been used in a wide variety of advanced areas, including pharmaceutical and biomedical applications, in large part due to their extraordinary properties such as outstanding electrical conductivity, high mechanical strength, ease of functionalization, large surface area, and high biocompatibility. Graphene and its polymeric composites have been used for the fabrication of advanced bioactive scaffolds to serve tissue regeneration. The unique features of graphene-polymer composites make them very suitable scaffolds for the delivery of the cells and necessary substances to the damaged tissues, in particular bone, cartilage, and electroactive tissues. In this review, we elaborate on the graphene-incorporated polymeric composite scaffolds and comprehensively discuss their applications.
... Hence, it can be concluded that functionalization of SiNS offers an effective strategy for the tailoring of their NLO response. Finally, for comparison purposes, the results of some recent studies, 46,47 concerning the NLO response of some graphene derivatives (as, e.g., graphene oxide (GO), methoxythiophenolmodified fluorographene (CF-MTP), and (dimethylamino)thiophenol-modified fluorographene (CF-DMATP)), obtained under similar experimental conditions, are presented in Table 1. As can be seen from this table, the presently studied SiNSs were found to exhibit the largest NLO response (ca., thirdorder susceptibility χ (3) ) among these 2D systems. ...
Silicene, the silicon analogue of graphene, represents a new class of two-dimensional (2D) materials, which shares some of the outstanding physical properties of graphene. Furthermore, it has the advantage of being compatible with the current Si-based technology. However, this 2D material is not stable and is quite prone to oxidation. The hydride-terminated silicene, called silicane, is a more stable form of 2D silicon, if functionalized via, for example, the hydrosilylation reaction. In this work, the third-order nonlinear optical (NLO) properties of two functionalized silicanes, namely hydride-terminated silicon nanosheets (SiNS-H) and 1-dodecene-functionalized silicon nanosheets (SiNS-dodecene), are accessed and compared to those of single-layer graphene, under 35 ps, 532 and 1064 nm excitation. The present results show that the functionalized silicanes exhibit comparable and even higher NLO response than that of single-layer graphene, making them strong competitors of graphene and very interesting candidates for future photonic and optoelectronic applications.
... As can be seen form this table, the OL on values of the FG-OAxs (all dispersions prepared exhibiting 70% linear transmittance at each excitation wavelength) were all found to be quite low, both under visible and infrared excitation, and in the latter case being substantially smaller. This finding suggests clearly that the FG-OAxs are much more efficient optical limiters when compared, for example, to other materials generally considered as benchmark materials for optical limiting, e.g., some C 60 -toluene solutions (with OL on = 0.2 J cm −2 ) [31] and carbon black suspensions (with OL on = 2.2 J cm −2 ) [32]. ...
Fluorographene has been recently shown to be a suitable platform for synthesizing numerous graphene derivatives with desired properties. In that respect, N-octylamine-modified fluorographenes with variable degrees of functionalization are studied and their nonlinear optical properties are assessed using 4 ns pulses. A very strong enhancement of the nonlinear optical response and a very efficient optical limiting action are observed, being strongly dependent on the degree of functionalization of fluorographene. The observed enhanced response is attributed to the increasing number of defects because of the incorporation of N-heteroatoms in the graphitic network upon functionalization with N-octylamine. The present work paves the way for the controlled covalent functionalization of graphene enabling a scalable access to a wide portfolio of graphene derivatives with custom-tailored properties.
... Among other nanomaterials, recently different two dimensional (2D) nanomaterials [e.g., graphene and transition metal dichalcogenides (TMDs)] have been considered to be as potential candidates for nonlinear optical (NLO) applications because of their close confinement of electrons in the 2D plane [1][2][3][4][5][6][7][8][9]. Extensive studies on TMDs have revealed that these nanomaterials are showing much better linear and NLO properties than those of the Graphene due to the transformation of indirect bandgap to direct bandgap nature on thinning of the layer numbers [1][2][3][4][5][6][7][8][9][10][11]. Different TMDs (e.g., MoS 2 , MoSe 2 , WSe 2 , etc.) based 2D nanomaterials are such promising class of optical materials and because of their large nonlinearity they have been used in optical switching, Q-switching, mode-locking, and other optical limiting devices [6][7][8]10]. ...
By employing the Z-scan technique, the nonlinear optical (NLO) properties of multi-layered WS2 nanosheets (WNSs) are investigated using pulsed (10 ns) laser irradiation having wavelength of 532 nm. In the trilayer WNSs, the transformation from saturable absorption (SA) to reverse saturation absorption (RSA) is clearly observed only when the magnitude of incident pump intensity exceeds 0.68 GW/cm². The saturation intensity in the case of SA for the used sample is found to be ~0.53 ± 0.03 GW/cm². The SA behaviour appears at low intensity due to one photon absorption (1PA) originated from the direct transition at B excitonic peak. This is confirmed from the measured photoluminescence properties of trilayer WNSs. Further, with the increase of laser intensity, the transformation of 1PA to two-photon absorption (2PA) occurs only for trilayer WNSs. It is observed that at the highest used intensity of 0.93 GW/cm², trilayer WNSs exhibits a large 2PA. A comprehensive analysis of the experimental data of Z-scan enables us to determine a value of ~1.42 ± 0.01 cm/GW for the highest 2PA coefficient (β2PA) and this value is ~1.5 times higher than those obtained for the multilayer and penta-layer WNSs. The calculated value of the imaginary part of the third-order NLO susceptibility (Im χ⁽³⁾) of the trilayer WNSs is ~4.24 × 10⁻¹³ esu. The properties of transition from SA to RSA in thinned layered of WNSs make these materials favourable for designing different optoelectronic devices.
... The normalized CA data are fitted with transmission eq 4 to calculate the nonlinear phase shift (ΔΦ 0 ) induced under consideration of third-order optical nonlinearity. 40,43,46 T z x ...
... Meanwhile, owing to the electronic transitions, the NLO properties of GO show wavelength-dependent characteristics [16]. Unfortunately, to the best of our knowledge, previous studies on the χ (3) of GO have been carried out only at some discrete wavelengths, such as at 532 nm reported by Khanzadeh et al. [17] and Biswas et al. [18], or at 1064 nm investigated by Liaros et al. [19]. In consequence, the dispersion of χ (3) in GO is deserved to be determined experimentally in the continuous visible region. ...
We experimentally determined the dispersion of third-order optical susceptibility χ⁽³⁾ of graphene oxide (GO) in the visible region (450 - 750 nm) by combining spectroscopic ellipsometry and ultrafast pump and probe spectroscopy in the femtosecond regime. In order to mitigate the damage of wide-spectrum laser to photonic devices, GO has become a promising material for optical limiting (OL) devices. However, there is no report about the χ⁽³⁾ dispersion of GO, which is a complex quantity that directly corresponds to nonlinear refraction and absorption and is a crucial parameter for the manipulation and application of its OL properties. Here, we identified that the linear optical response of GO shows a flat dispersion in the visible region. In contrast, its nonlinear optical response exhibits saturable absorption (SA) at the short wavelength and reverse saturable absorption (RSA) at the long wavelength. These results propel the application of GO in the broadband OL devices based on the RSA behavior. In addition, by controlling the fraction of sp² and sp³ hybridizations, it also provides opportunities to tailor the NLO properties and OL performance of GO.
... a(l) and a 0 are expressed as the total and linear absorption coefficient, respectively. The total absorption is the sum of SA and 2PA, which is expressed by Eq. 2 [52][53][54]. In Eq. 2, the first part of the equation is used to indicate the SA behavior, and the second part is used to indicate the 2PA behavior. ...
Graphdiyne (GDY) is an emerging carbon allotrope consisting of sp- and sp²-hybrid carbon atoms. The sp-hybrid carbon–carbon triple bond structure with strong d–π interaction has endowed GDY special nonlinear absorption (NLA) properties, which is different from graphene. As a starting monomer for synthesizing GDY, hexakis[(trimethylsilyl)ethynyl]benzene (HEB-TMS) also owns the carbon–carbon triple bond (sp-) and the benzene ring (sp²-) structures (similar to GDY), which stimulates us to explore the NLA properties of HEB-TMS. In this work, two-dimensional (2D) nanosheets of HEB-TMS are successfully prepared using a liquid-phase exfoliation method with the thicknesses of 3.49 ~ 4.47 nm. And the broadband NLA properties are researched using an open-aperture Z-scan method (from ultraviolet to infrared waveband). The results demonstrate that HEB-TMS owns excellent NLA characteristics in visible light waveband. The excellent optical limiting properties of HEB-TMS provide the possibility of application in the protection of human eyes and precision optical component in visible light.
... Specifically, graphene shows remarkable optoelectronic properties and optical nonlinearities with ultrafast response times and a broad spectral range. Recently, numerous nonlinear optical phenomena of graphene have been extensively studied and experimented, such as harmonic generation, frequency mixing, optical rectification and photon drag effect [33][34][35][36][37], which can lead to the development of applications like all-optical switches, THz transistors, optical power limiting, and fast optical communication [38][39][40][41]. ...
Since the isolation of graphene in 2004, a large amount of research has been directed at 2D materials and their applications due to their unique characteristics. Compared with the noble metal plasmons in the visible and near-infrared frequencies, graphene can support surface plasmons in the lower frequencies of terahertz (THz) and midinfrared. Especially, the surface conductivity of graphene can be tuned by either chemical doping or electrostatic gating. As a result, the idea of designing graphene metasurfaces is attractive because of its ultra-broadband response and tunability. It has been demonstrated theoretically and experimentally that the third-order nonlinearity of graphene at the THz frequency range is exceptionally strong, and graphene has smaller losses with respect to noble metals. These features make graphene a promising candidate to enhance nonlinear effects at the far-infrared and THz frequencies. In this thesis, we present several designs to explore electromagnetic applications of graphene metasurface. Theoretical and simulation studies are carried out to design tunable THz polarizers, amplifiers, coherent perfect absorbers and to achieve enhanced nonlinear effect. These studies on the applications of monolayer graphene demonstrate prospective potentials of graphene in THz sensing, imaging, modulators, and nonlinear THz spectroscopy. Adviser: Christos Argyropoulos
... The MoS 2 films with different sizes and a thickness of 75 nm show SA, which can be described by Model 1. σ 1 ∕σ 0 is vital in assessing SA and RSA. RSA occurs if the absorption cross-section of excited state is larger than that of ground state, which results in optical limiting effects [57]. Otherwise, SA occurs [20,26]. ...
Understanding and controlling defect in two-dimensional materials is important for both linear and nonlinear optoelectronic devices, especially in terms of tuning nonlinear optical absorption. Taking advantage of atomic defect formed easily by smaller size, molybdenum disulfide nanosheet is prepared successfully with different size by gradient centrifugation. Interestingly, size-dependent sulfur vacancies are observed by high-resolution X-ray photoelectron spectroscopy, atomic force microscopy, and transmission electron microscopy. The defect effect on nonlinear absorption is investigated by Z-scan measurement at the wavelength of 800 nm. The results suggest the transition from saturable absorption to reverse saturable absorption can be observed in both dispersions and films. First principle calculations suggest that sulfur vacancies act as the trap state to capture the excited electrons. Moreover, an energy-level model with the trap state is put forward to explain the role of the sulfur vacancy defect in nonlinear optical absorption. The results suggest that saturable and reverse saturable absorption originate from the competition between the excited, defect state and ground state absorption. Our finding provides a way to tune the nonlinear optical performance of optoelectronic devices by defect engineering
... x samples were lacking this feature, indicating their lower oxidation degree. 13,24 The oxidation degree of the samples was also confirmed by means of high-resolution X-ray photoelectron spectroscopy (HR-XPS) which can reveal more precisely, among other things, the oxygen and sp 2 carbon contents. It should be noted, that very similar to the present GO 1 ...
In the present work we report on the effect of the size and the degree of oxidation on the third-order nonlinear optical response and the optical limiting action of water dispersed graphene oxide (GO) sheets. The results show clearly that both the nonlinear optical third-order susceptibility χ(3) and the optical limiting threshold depend importantly on the size of the GOs, scaling linearly with the lateral size. In addition, it was found that the similar size but highly oxidized GO samples exhibited lower nonlinear optical response than the less oxidized ones, while their optical limiting efficiency was found to be slightly affected by the degree of oxidation, increasing with the increase of the size of the GO sheets. The optical limiting thresholds of the graphene oxide samples were found to be very low, comparable to some of the benchmark optical limiting materials. The observed size dependent nonlinear optical response of the GOs seems to be closely connected to the size of the conjugated areas of the graphenic sheets. The findings suggest a straightforward and efficient way for preparing graphene oxide sheets exhibiting custom made nonlinear optical properties for specific applications in optoelectronics and photonics.
The nonlinear absorption (NLA) properties of ITO thin films were performed by utilizing femtosecond (100 fs), a high-repetition rate (80 MHz), and near-infrared (NIR) (750–820 nm) laser pulses. A radio frequency (RF) magnetron sputtering system was used to prepare ITO thin films of two different thicknesses. A scanning electron microscope (SEM) was used to determine the film thickness, and a UV-Visible spectrophotometer was used to observe the linear optical properties of the thin films. The open aperture Z-scan technique's nonlinear absorption studies of ITO thin films exhibited a reverse saturable absorption. The NLA properties of the ITO films varied depending on ITO thickness, incident laser power, and excitation wavelength, attributed to the increasing localized defect states in the band gap. The nonlinear absorption coefficient of 6×10 − 7 cm/W and 9.7×10 − 7 cm/W were measured for 170 and 280 nm film thicknesses, respectively. In contrast to the film thickness, the nonlinear absorption coefficient was inversely proportional to the excitation laser wavelength. Additionally, the optical limiting of ITO thin films was investigated, and it was found that there is a clear correlation between optical limiting and thin film thickness.
Materials exhibiting multi-photon absorption (MPA) are of significant interest for a range of applications including microfabrication, bio-imaging and sensing, and photodynamic therapy. Amongst the possible MPA materials, metal alkynyl complexes have attracted significant recent interest because the collinear metal and alkynyl ligand promote strong electron delocalization and intra-molecular charge transfer, resulting in complexes that can display outstanding MPA behavior. This review summarizes recent progress with metal alkynyl complexes as potential MPA materials, with an emphasis on structure-MPA property relationships that signpost the route to efficient multi-photon absorbers. A brief introduction to the theory of nonlinear optics that underpins MPA and an overview of the key experimental techniques to determine molecular MPA properties are also provided.
Reduced graphene oxide (rGO) was synthesized successfully from dead leaves of neem trees using a novel synthesis method comprising combustion, washing, and drying. The synthesized carbonaceous material was subjected to systematic characterization analysis. The rGO material was subjected to X-ray powder diffraction analysis to determine the grain size and other structural parameters. The existence of defect and graphitic band was confirmed by FT-Raman analysis. The presence of a 2D band around 2700 cm−1 indicated the formation of multi-layered graphene. SEM analysis was used to examine the structural morphology of the synthesized material. FTIR spectra revealed the information about the spectral properties of rGO. Compositional analysis revealed the presence of carbon and other contents in the specimen. The title material may be used in optical power limiters, according to z-scan and optical limiting analysis. The results indicate that the cost of synthesis would be significantly reduced when done on a large scale, using this procedure. Furthermore, rGO produced by this method is environmentally friendly, nontoxic and has a high yield.
The Z-scan technique uses a single beam that can be used for observing the nonlinear or optical limiting properties of materials. For the first time, the Z-scan properties dependent on the polarization of 2D carbon nanomaterial suspension were experimentally investigated using optical Z-scan technology. The Z-scan curves of graphene and graphene oxide (GO) in N-methyl-2-pyrrolidinone suspensions exhibited strong polarization-dependent characteristics. In paper, a reverse saturated absorption (RSA) dip surrounded the lens focus when the horizontal polarized beam was focused in the suspension, and two saturated absorption (SA) peaks appeared adjacent to the dip. However, for the vertical polarized beam, only one RSA dip surrounded the lens focus, and the threshold was higher than the SA for a horizontally polarized beam. The transmission of RSA for the GO suspension was evidently lower than that of the graphene suspension. The polarization-dependent characteristic can be ascribed to the laser-induced alignment in case the suspension is moved in or out of the beam focal point. Furthermore, the polarization-dependent 2D carbon nanomaterial suspension can be applied in several practical purposes such as 2D material-based optical and opto-fludic devices.
In this work, we study the boosted optical nonlinearities of graphene oxide (GO) films by laser direct writing with femtosecond laser (532 nm, 330fs) excitation. We firstly prepare the uniform GO films by vacuum filtration method, which are then partly reduced by commercial carbon dioxide laser machine. The morphology, structure and luminescence traits of both the pristine and reduced GO are further characterized by SEM, XRD, Raman spectra, XPS, PL and UV–Vis absorption spectrum. Moreover, their third-order optical nonlinearities (TONs) are measured by the femtosecond laser Z-scan technique. The experimental results show that the reduced GO films take on stronger TONs and the related degree of enhancement depends on the spot size of laser processing. In particular, when the processed diameter is around 400 μm, the optical nonlinear absorption and refraction coefficients of the reduced GO are −2.9 × 10⁻⁷ m/W and 2.5 × 10⁻¹⁵ m²/W, respectively, which are in turn 4 and 2 times higher than that of GO film. Our results provide powerful backing for the GO-based applications, such as ultra-fast optical devices, super-resolution imaging technology and photodetector.
High quality graphene production is prerequisite for good performance in nonlinear optics application such as fast optical communications, all-optical switching, and optical limiting. Graphene journey begins with the method of synthesizing graphene which need to be simple, fast, and environmentally friendly. Hence, we introduce the method by exfoliating graphite by electrochemical route to produce good quality functionalized graphene for various nonlinear optics application. In this work, functionalized graphene flakes are synthesis by using two different electrodes; furnaced graphite rod (Gr-FG) and non-furnaced graphite electrode (Gr-NFG). Visual inspection on the synthesized Gr-FG and Gr-NFG show dark murky color solutions give the impression of high yield functionalized graphene flakes. Further observation under transmission electron microscopy (TEM), selected area electron diffraction (SAED), and UV–vis and Raman analysis confirm the good quality functionalized graphene structure. The nonlinear optical behavior of the functionalized graphene was accessed via Z-scan technique with 637 nm laser source operating in continuous mode with simultaneous monitoring of the close and open aperture signal. Close aperture profile of Gr-FG and Gr-NFG display nonlinear refraction, whereas open aperture profile shows reverse saturable absorption (RSA). Equation fitting reveals higher n2 magnitude for Gr-FG compared to Gr-NFG, but the later possess higher magnitude of β. Further analysis on the 3rd order of optical nonlinearity by z-scan technique reveal the admirable value at the range of 10⁻⁶ esu. Optical limiting performance conducted via transmittance-based measurement shows superior limiting of Gr-NFG compared to Gr-FG.
As a representative transition metal oxide, cupric oxide (CuO) has attracted a lot of interest in miscellaneous fields. In the present work, the prominent third-order nonlinear optical (NLO) features of CuO nanosheets were demonstrated via the typical Z-scan technique at 1 μm. The open-aperture (OA) Z-scan measurements at different intensities clearly showed that CuO nanosheets possessed the saturable absorption (SA), reverse saturable absorption (RSA) and optical limiting behaviors. The closed-aperture (CA) Z-scan technology was implanted to investigate the nonlinear refractive index and the third-order nonlinear susceptibility. In virtue of the strong nonlinear optical absorption properties of CuO nanosheets, a stable all-solid-state mode-locked laser with the as-prepared CuO nanosheets as saturable absorber at 1.06 μm was realized for the first time. Our work confirmed that CuO nanosheets exhibited outstanding NLO properties, which might stimulate the development in ultrafast photonics and nonlinear optics.
Herein, a simple, low‐cost, and scalable process is developed to prepare the reduced graphene oxide (rGO) thin films (TFs) with strong optical nonlinearity. To do so, a chemical reduction method (using inorganic agent hydroiodic acid) and drop‐casting technique are used. Optical nonlinearity of the prepared thin rGO film is measured by the Z‐scan technique at low light intensity (continuous‐wave wavelength of 632 nm). The result of optical nonlinearity responses is illustrated by a remarkable nonlinear refraction index (n2 ≈ 10⁻⁴ cm² W⁻¹) as well as a considerable nonlinear absorption coefficient (β = 1.43 × 10⁻⁸ cm² W–1) compared with similar reported results. Moreover, experimental results show that the prepared film enjoys a positive nonlinear refractive index with strong optical nonlinearity. Results also confirm that the changes made in optical absorption of rGO TFs are due to state filling effects and the optical nonlinearity proportional to the carriers’ density is in fact due to thermal effects of SiO2 substrate.
Bismuth telluride/reduced graphene oxide (Bi2Te3/rGO composites) was prepared by solvent-thermal method, and Bi2Te3/rGO-PVA (Polyvinyl alcohol) thin film was synthesized from drop coating method. The third-order nonlinear optical properties (NLO) and optical limiting (OL) performances of the solution samples and the film samples were studied using Z-scan test at the laser wavelength of 532 nm and 1064 nm with 10 Hz repetition frequency and 4 ns pulse width. In comparison with Bi2Te3, rGO and Bi2Te3+rGO (Bi2Te3 and rGO are mechanically stirred together), whether Bi2Te3/rGO solution sample or Bi2Te3/rGO-PVA film sample possess larger third order nonlinear absorption coefficients (β) and lower limiting thresholds due to the charge transfer and synergistic effect between Bi2Te3 and rGO. The limiting thresholds of Bi2Te3/rGO-PVA thin film samples (~0.19 J/cm² at 532 nm and ~0.52 J/cm² at 1064 nm) are lower than that of Bi2Te3/rGO solution due to much higher concentration in the film at the same level of linear transmission. The Bi2Te3/rGO-PVA thin film could be the promising optical limiting materials.
Nonlinear optical nanostructured materials are gaining interest as optical limiters for various applications. Here, all-inorganic halide perovskite quantum dots (PQDs, SiO2@CsPbX3 (X = Cl, Br, I) QDs) with tunable composition were prepared via ligand assisted reprecipitation, using 3-aminopropyltriethoxysilane as a ligand. The formation of the SiO2@CsPbX3 QDs was confirmed by transmission electron microscopy, X-ray diffraction, infrared spectroscopy, ultraviolet–visible absorption spectroscopy and photoluminescence spectroscopy. The composition-dependent optical limiting (OL) behavior of the SiO2@CsPbX3 QDs was observed using nanosecond and picosecond laser pulses at a wavelength of 532 nm. The SiO2@CsPbBr3 QDs exhibit favorable OL properties. Their OL threshold for the nanosecond laser pulse is 1.68 J/cm², which is comparable to that of carbon nanotube suspension (a benchmark optical limiter). The presence of chloride or iodide in the SiO2@CsPbX3 QDs leads to weaker OL performance. The OL behavior of the SiO2@CsPbBr3 QDs is attributed to the narrow band gap, large average size, abundant charge carriers under laser excitation and high stability. The OL mechanism was investigated using the open-aperture and closed-aperture techniques. The OL behavior of the SiO2@CsPbX3 QDs is largely attributed to the combined mechanisms of nonlinear absorption and nonlinear refraction. These results reveal the physical processes of the composition-dependent OL properties of the CsPbX3 QDs. These findings provide a means to tailor the OL response of PQDs by controlling the halide ion ratio.
Organic and organometallic π-conjugated molecules with inherent nonlinear optical (NLO) response have been attracted great interest due to their controllable properties via rational structure modifications. However, most of the state-of-the-art materials such as porphyrins, phthalocyanines, and diacetylenes exhibit NLO response at visible-light regions. Recently, diketopyrrolopyrrole (DPP) based donor-acceptor (D-A) type π-conjugated copolymers have been found exhibiting NLO response which can reach up to 1064 nm. However, the design rationality of structure toward NLO properties is not well understood. Herein, four alternating DPP-based copolymers are constructed by using electron donors of 2-phenylpyridine for P1, 2-thienylpyridine for P2 and their Pt(II)-incorporated moieties for P1Pt and P2Pt. All copolymers display intense intramolecular charge transfer (ICT) processes, the ICT absorption can be extended to near-infrared (NIR) region due to the strong D-A interaction of π-conjugated backbone; The variation tendency of optical bandgaps estimated from the onset of ICT absorption is of P1 (1.60 eV) > P1Pt (1.56 eV) > P2 (1.47 eV) > P2Pt (1.44 eV). Open- and close-aperture Z-scan experiments disclosed that all copolymers exhibit broadband (532 and 1064 nm) NLO properties due to the synergistic effect of excited state absorption and ICT process upon 8 ns as well as 25 ps laser pulses. Pt(II)-incorporation can promote or switch the NLO properties due to the efficient triplet-state absorption introduced by the heavy-atom effect. The improvement of NLO properties are of P1 < P1Pt < P2 < P2Pt, which are consistent well with the decrease tendency of copolymer bandgaps. These results will provide guidelines for the rational design of materials toward broadband NLO responses and advanced applications.
Liquid suspensions of carbon nanotubes, graphene and transition metal dichalcogenides have exhibited excellent performance in optical limiting. However, the underlying mechanism has remained elusive and is generally ascribed to their superior nonlinear optical properties such as nonlinear absorption or nonlinear scattering. Using graphene as an example, we show that photo-thermal microbubbles are responsible for the optical limiting as strong light scattering centers: graphene sheets absorb incident light and become heated up above the boiling point of water, resulting in vapor and microbubble generation. This conclusion is based on direct observation of bubbles above the laser beam as well as a strong correlation between laser-induced ultrasound and optical limiting. In-situ Raman scattering of graphene further confirms that the temperature of graphene under laser pulses rises above the boiling point of water but still remains too low to vaporize graphene and create graphene plasma bubbles. Photo-thermal bubble scattering is not a nonlinear optical process and requires very low laser intensity. This understanding helps us to design more efficient optical limiting materials and understand the intrinsic nonlinear optical properties of nanomaterials.
The optical properties of graphene-based nanomaterials have attracted much recent attention. This article provides an overview of recent advances in the study of linear and nonlinear optical transitions associated mostly with tailored energy bandgaps. In particular, the optical absorption characteristics and photoluminescence emissions due to various induced bandgaps and, in some cases, the formation of graphene quantum dots are highlighted. Nonlinear optical properties of these materials are reviewed with an emphasis on optical limiting through both nonlinear absorption and scattering mechanisms.
The optical nonlinear absorption of the aqueous solution of platinum nanospheres protected by poly (N-vinyl-2-pyrrolidone) was investigated using open aperture Z-scan method with nanosecond pulse laser at the wavelength of 532 run. A shift from saturable absorption to reverse saturable absorption was observed at higher input pump intensities. The transition process was analyzed using a phenomenological model based on nonlinear absorption coefficient and saturation intensity. (c) 2005 Elsevier B.V. All rights reserved.
The nonlinear optical (NLO) and optical limiting (OL) properties of graphene families, including graphene oxide nanosheets, graphene nanosheets (GNSs), graphene oxide nanoribbons (GONRs), and graphene nanoribbons (GNRs), were investigated at 532 and 1064 nm using a nanosecond regime. GNSs, GONRs, and GNRs exhibited broadband NLO and OL properties. Reduced graphene samples exhibited stronger NLO and OL responses than their graphene oxide precursors because of their increased crystallinity and conjugation. Nonlinear scattering and two-photon-absorption were found to have strong effects on the NLO and OL responses of the graphene nanostructures.
Under intense laser excitation, thin films and suspensions of graphite and its nanostructure, including carbon black, nanotubes, few-layer graphenes and graphene oxides, exhibit induced transparency due to saturable absorption. This switches to optical limiting only at very high fluences when induced breakdown gives rise to microbubbles and microplasmas that causes nonlinear scattering. Here, we show that dispersed graphenes, in contrast, can exhibit broadband nonlinear optical absorption at fluences well below this damage threshold with a strong matrix effect. We obtained, for nanosecond visible and near-infrared pulses, a new benchmark for optical energy-limiting onset of 10 mJ cm-2 for a linear transmittance of 70%, with excellent output clamping in both heavy-atom solvents and polymer film matrices. Nanosecond pump-probe spectroscopy in chlorobenzene reveals that the nanographene domains switch from the usual broadband photo-induced bleaching to a novel reverse saturable absorption mechanism with increasing excitation densities across this threshold.
The chemistry of graphene oxide is discussed in this critical review. Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure. Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed. This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references).
Graphene with its peculiar and exceptional properties has been widely used in the preparation of next generation functional nanocomposites. However, future development of graphene and graphene-based composites crucially depends on the fundamental understand-ings of their hierarchical structures and dynamical behaviors provided by multiscale modeling and simulation. In the beginning of this review, some computational methods that have been applied extensively in the area of graphene and graphene-based composites are introduced, covering from Quantum Chemistry approach, Molecular Dynamics method to Monte Carlo sim-ulation technique. Then the applications of these methods to various aspects of graphene and graphene-based composites are discussed in some detail. Particular emphasis is laid on researches that explore the physical properties, interacting mechanisms, and potential appli-cations of graphene-based materials. Finally, future challenges and perspectives in modeling and simulation of graphene-based composites are addressed.
The nonlinear optical properties of graphene oxide (GO) were investigated at 532 nm in nanosecond and picosecond regimes. Results show that two-photon absorption dominates nonlinear absorption process of GO in the case of picosecond pulses, while excited state nonlinearities play an important role in the case of nanosecond pulses. Additionally, we compared nonlinear optical properties of three different dimensional carbon-based materials (two-dimensional graphene, one-dimensional carbon nanotube, and zero-dimensional fullerene) in nanosecond and picosecond regimes, respectively. The nonlinear mechanism of GO is distinctly different from nonlinear scattering of carbon nanotube and excited state nonlinearity of fullerene.
This paper reviews recent advances in the nanotube and graphene polymer composites synthesized in our laboratories for laser protection application, i.e., OL. We first discuss the mechanisms involved in the polymer nanocomposites for OL and the Z-scan technique used to measure the nonlinear optical properties of the materials in question. Subsequently, the design, synthesis, characterization, and OL properties of the representative nanotube and graphene polymer composites are introduced, followed by a prospect for use of carbon nanomaterial polymer composites for optical limiting.
A soluble graphite oxide (GO) axially substituted gallium phthalocyanine (PcGa) hybrid material (GO-PcGa) was for the first time synthesized by the reaction of tBu(4)PcGaCl with GO in anhydrous DMSO at 110 °C in the presence of K(2)CO(3). The formation of a Ga-O bond between PcGa and GO has been confirmed by x-ray photoelectron spectroscopy. In contrast to GO, the D and G bands of GO-PcGa in the Raman spectrum are shifted to the lower wavenumbers by Δν = 11 and 18 cm(-1), respectively. At the same level of concentration of 0.1 g l(-1), GO-PcGa exhibit much larger nonlinear optical extinction coefficients and strong optical limiting performance than GO, tBu(4)PcGaCl and C(60) at both 532 and 1064 nm, implying a remarkable accumulation effect as a result of the covalent link between GO and PcGa. GO-PcGa possesses three main mechanisms for the nonlinear optical response-nonlinear light scattering, two-photon absorption and reverse saturable absorption for the 532 nm pulses and nonlinear light scattering for the 1064 nm pulses. tBu(4)PcGaCl does not make any significant contribution to the optical limiting at 1064 nm, while GO-PcGa has a much greater optical limiting response than GO at this wavelength, this suggesting that the PcGa moiety could certainly play an unknown but important role in the GO-PcGa material system.
Graphene is an intriguing material with properties that are distinct from those of other graphitic systems. The first samples of pristine graphene were obtained by 'peeling off' and epitaxial growth. Recently, the chemical reduction of graphite oxide was used to produce covalently functionalized single-layer graphene oxide. However, chemical approaches for the large-scale production of highly conducting graphene sheets remain elusive. Here, we report that the exfoliation-reintercalation-expansion of graphite can produce high-quality single-layer graphene sheets stably suspended in organic solvents. The graphene sheets exhibit high electrical conductance at room and cryogenic temperatures. Large amounts of graphene sheets in organic solvents are made into large transparent conducting films by Langmuir-Blodgett assembly in a layer-by-layer manner. The chemically derived, high-quality graphene sheets could lead to future scalable graphene devices.
A sensitive single-beam technique for measuring both the nonlinear
refractive index and nonlinear absorption coefficient for a wide variety
of materials is reported. The authors describe the experimental details
and present a comprehensive theoretical analysis including cases where
nonlinear refraction is accompanied by nonlinear absorption. In these
experiments, the transmittance of a sample is measured through a finite
aperture in the far field as the sample is moved along the propagation
path ( z ) of a focused Gaussian beam. The sign and magnitude of
the nonlinear refraction are easily deduced from such a transmittance
curve ( Z -scan). Employing this technique, a sensitivity of
better than λ/300 wavefront distortion is achieved in n
<sub>2</sub> measurements of BaF<sub>2</sub> using picosecond
frequency-doubled Nd:YAG laser pulses
Motivated by both its graphene-oriented applications and its own remarkable properties, interest in graphene oxide (GO) has widely spread across many disciplines. In parallel to the rapid progress of research, industrial-scale production of GO has emerged. GO is highly energetic, thermally unstable and can readily undergo exothermic disproportionation reactions to produce chemically modified graphene under mild heating conditions. This Review highlights the challenges and opportunities associated with GO's thermal instability such as the potential fire risk during large scale production and methods of mitigation, energy efficient way to reduce GO, photothermal patterning and sintering of graphene/polymer composites, and new syntheses using GO as an in situ power source to make nanoparticle decorated graphene composites for energy storage and catalysts.
Graphene fluoride (G.F.) is the youngest in the family of graphene derivatives. Being optically transparent in the visible spectrum, G.F. is unique among other low dimensional carbon materials. In this work, colloidal dispersions are prepared by aqueous-phase exfoliation of graphite fluoride through non-covalent functionalization with perfluorooctanoate units. Light scattering and electrophoresis reveal the exceptional stability of the dispersion, while the formation of ultrathin G.F. sheets is verified by electron and atomic force microscopy. In addition, for the first time it is reported that G.F. colloids exhibit high third-order nonlinear optical response, suggesting their potential application in photonic and opto-electronic devices.
In this work, we report a theoretical analysis of three-, four-and five-photon absorption process using the open aperture Z-scan tech-nique. The normalized transmittance equations presented here can be used to fit the experimental data, allowing the determination of material's multi-photon absorption cross-section. Through simulations, we observed the expected sharpening of the Z-scan curve for higher order nonlinear absorption. The normalized transmittance change as a function of the excitation irradiance displays distinct slopes for process with distinct number of photons, which can be used for determining the origin of the nonlinear processes. Optical limiting curves were also simulated for multi-photon absorption processes, demonstrating that high limiting thresholds occur for higher order processes. Ó 2007 Elsevier B.V. All rights reserved.
A study was conducted to prepare organic-solution-processable functionalized-graphene (SPF Graphene) hybrid material with porphyrins and to demonstrate its photophysical properties including optical-limiting properties. The synthesis of the porphyrin-graphene nanohybrid, 5-4 (aminophenyl)-10, 15, 20-triphenyl porphyrin (TPP) and graphene oxide molecules covalently bonded using an amide bond was carried out using an amine-functionalized prophyrin (TPP-NH2) and graphene oxide in N,N-dimethylformamide (DMF). FTIR, UV-vis absorption, and TEM studies were also carried out to examine covalent functionalization of the graphene. It was observed that the fluorescence of photo-excited TPP-NH2 was quenched by a possible electron-transfer process. These organic solution-processable functionalized graphene material can be used for light harvesting and solar-energy conversion materials for optoelectronic devices.
Elements of the theory of nonlinear optics frequency doubling and mixing optical parametric generation, amplification, and oscillation characterization of second order nonlinear optical materials properties of selected second order nonlinearoptical materials nonlinear index of refraction characterization of nonlinear refractive index materials optical properties of selected third order nonlinear optics materials nonlinear absorption experimental techniques in nonlinear absorption ultrafast characterization techniques laser flash photolysis nonlinear absorption properties of selected materials stimulated Raman scattering stimulated Brillouin scattering properties of selected stimulated light-scattering materials theelectro-optic effect.
Graphene oxide (GO) thin films on glass and plastic substrates were found to display interesting broadband nonlinear optical properties. We have investigated their optical limiting activity for femtosecond laser pulses at 800 and 400 nm, which could be tuned by controlling the extent of reduction. The as-prepared GO films were found to exhibit excellent broadband optical limiting behaviors, which were significantly enhanced upon partial reduction by using laser irradiation or chemical reduction methods. The laser-induced reduction of GO resulted in enhancement of effective two-photon absorption coefficient at 400 nm by up to similar to 19 times and enhancement of effective two- and three-photon absorption coefficients at 800 nm by similar to 12 and similar to 14.5 times, respectively. The optical limiting thresholds of partially reduced GO films are much lower than those of various previously reported materials. Highly reduced GO films prepared by using the chemical method displayed strong saturable absorption behavior.
MEMBRANES composed of bilayers of amphiphiles such as phospholipids
generally exhibit two-dimensional liquid-like structure within the layers. When the constituent molecules of such a membrane are permanently cross-linked to
each other, the membrane becomes less flexible, forming a two-dimensional
solid. Solid membranes are expected to exhibit very different behaviour from their liquid counterparts1–3, including transitions between a two-dimensional flat phase, a crumpled phase of fractal dimension 2.5
and a compact, three-dimensional phase. Experimental evidence for the crumpled
phase has, however, been lacking. As this phase was not observed in computer
simulations4–6, it has been suggested that it may
always be absent for self-avoiding (and therefore all real)
membranes4–6. To the contrary, we report here the
experimental observation of the crumpled conformation in an aqueous suspension
of graphite oxide membranes. Static light scattering measurements indicate the
presence of membrane conformations with a fractal dimension of 2.54
±0.05. As the intra-membrane affinity is enhanced by changing the
composition of the solvent, the membranes collapse to a compact
configuration.
The ultrafast relaxation dynamics and nonlinear optical response in single- and few-layered graphene oxide (GO) were studied by ultrafast optical differential transmission spectroscopy and Z-scan technique using various pump intensities. It was found that charge carriers with subpicosecond-to-picosecond dynamics from sp2-hybridized domains dominate the ultrafast response at low pump intensities, like graphene. Surprisingly, the influence of two-photon absorption from sp3-hybridized domains on the transient absorption signal becomes increasingly strong with pump intensities. On the basis of heterogeneous ultrafast dynamics of GO with saturable absorption in sp2 domains and two-photon absorption in sp3 domains, the nonlinear optical response can be tailored by manipulation of the degree and location of oxidation on GO sheets; this unravels the important role of sp3 domains in graphene optics and will facilitate the potential applications of GO in optoelectronics.Keywords: graphene oxide; ultrafast dynamics; nonlinear optical response; two-photon absorption; saturable absorption; Z-scan
Low-cost broad-band optical limiters based on nanographene have been studied, finding optical-limiting properties superior to those of current standards, carbon fullerenes (C60) solutions and carbon black suspensions. Further examination indicates that the presence of π conjugation improves the optical-limiting responses. Superior limiting performance is retained regardless of solvent viscosity and polarity, a unique feature of graphene not observed in C60 and carbon black. Graphene suspensions in organic solvents can work under 10 Hz laser pulses without losing excellent limiting performance. More significantly, outstanding limiting properties are also preserved in a gel matrix. These nanographene-based optical limiters can thus work in solutions and solid matrixes for devices used for protecting human eyes and optical sensors from high-power lasers.
Graphene, the two-dimensional sp2-hybridized carbon, is currently, without any doubt, the most intensively studied material. This single-atom-thick sheet of carbon atoms arrayed in a honeycomb pattern is the world's thinnest, strongest, and stiffest material, as well as being an excellent conductor of both heat and electricity. Despite the great application potential, it is worth mentioning that graphene itself possesses zero band gap as well as inertness to reaction, which weakens the competitive strength of grapheme in the field of semiconductors and sensors. The functionalization of pristine graphene sheets with organic functional groups has been developed for several purposes. The main purpose is the dispersibility of graphene in common organic solvents that is usually obtained after attachment of certain organic groups. The dispersion of graphene sheets in organic solvents is a crucial move toward the formation of nanocomposite materials with graphene.
The optical limiting action of C60 in toluene solution is mainly due to reverse saturable absorption (RSA). It is shown that the formalism describing nonlinear optical response due to instantaneous two-photon absorption can be used in the case of sequential two-photon absorption, yielding effective values of the relevant parameters of optical nonlinearity due to RSA. The effective two-photon absorption parameter beta eff and the effective nonlinear refractive index parameter gamma eff', which are related respectively to the imaginary and real parts of the effective third-order susceptibility chi eff(3) were measured by the z-scan technique as a function of fullerene concentration and of incident laser intensity and wavelength over the 420-640 nm region. The concentration dependence of these parameters indicates that the solution is optically thin as far as the ground state of C60 is concerned, whereas the wavelength dependence confirms the applicability of the formalism used in the sequential two-photon absorption model. Comparisons are made with other z-scan results on C60.
Graphene, which consists of a one-atom-thick planar sheet comprising an sp-bonded carbon structure with exceptionally high crystal and electronic quality, is a novel material that has emerged as a rapidly rising star in the field of material science. Facile electron transfer between graphene and redox species opens up opportunities for sensing strategies based on direct electron transfer rather than mediation. It is not surprising, therefore, that graphene has recently attracted great attention worldwide from the electrochemical community. Despite its short history, this 2D material has already revealed potential applications in electrochemistry, and remarkably rapid progress in this area has already been made. The oxygen functional groups have been identified as mostly in the form of hydroxyl and epoxy groups on the basal plane, with smaller amounts of carboxy, carbonyl, phenol, lactone, and quinone at the sheet edges.
An organic solution-processable functionalized graphene hybrid material with oligothiophene (6THIOP-NH-SPFGraphene) has been synthesized. The thermogravimetry analysis data shows that the hybrid is more stable than its parent graphene oxide as observed with an increased onset temperature. Ultraviolet–visible absorption and fluorescence emission data show that the attachment of the electron-acceptor group (graphene oxide sheet) onto the oligothiophene molecules results in an improved absorption than its parent compound in the whole spectral region and an efficient quenching of photoluminescence. The optical limiting properties were studied by using the open-aperture Z-scan measures at 532 nm, and the results show that 6THIOP-NH-SPFGraphene demonstrated a superior optical limiting effect, better than that of the benchmark optical limiting material C60.
This pH-potentiometric study explores the factors influencing the surface charge developed in aqueous dispersions of graphite oxide (GO) after a series of oxidation treatments. Surface charging curves demonstrate that lamellar surfaces of GO are negatively charged in the entire pH range studied. While these curves were found to be independent from the concentration of the GO suspensions, they were greatly affected by the solution conditions: increasing the pH and the ionic strength promotes the dissociation of acidic surface sites as weaker functional groups progressively participate in the ion exchange process, and the electrolyte provides an effective shielding for the surface charge. Surface densities of dissociated functional groups were determined by the proton binding isotherms and the specific surface areas of GO samples. BET surface areas provided irrationally high values for site densities, while surface areas calculated by geometrical considerations gave acceptable site densities. Formation of more and more oxygen-containing groups upon the subsequent oxidation steps, detected by IR spectroscopy and elemental analysis, resulted in the enhanced acidity of graphite oxide.
It is estimated that the world will need to double its energy supply by 2050. Nanotechnology has opened up new frontiers in materials science and engineering to meet this challenge by creating new materials, particularly carbon nanomaterials, for efficient energy conversion and storage. Comparing to conventional energy materials, carbon nanomaterials possess unique size-/surface-dependent (e.g., morphological, electrical, optical, and mechanical) properties useful for enhancing the energy-conversion and storage performances. During the past 25 years or so, therefore, considerable efforts have been made to utilize the unique properties of carbon nanomaterials, including fullerenes, carbon nanotubes, and graphene, as energy materials, and tremendous progress has been achieved in developing high-performance energy conversion (e.g., solar cells and fuel cells) and storage (e.g., supercapacitors and batteries) devices. This article reviews progress in the research and development of carbon nanomaterials during the past twenty years or so for advanced energy conversion and storage, along with some discussions on challenges and perspectives in this exciting field.
The defining characteristic of a nanomaterial is that its properties vary as a function of its size. This size dependence can be clearly observed in single-walled carbon nanotubes, where changes in structure at the atomic scale can modify the electronic and optical properties of these materials in a discontinuous manner (for example, changing metallic nanotubes to semiconducting nanotubes and vice versa). However, as most practical technologies require predictable and uniform performance, researchers have been aggressively seeking strategies for preparing samples of single-walled carbon nanotubes with well-defined diameters, lengths, chiralities and electronic properties (that is, uniformly metallic or uniformly semiconducting). This review highlights post-synthetic approaches for sorting single-walled carbon nanotubes - including selective chemistry, electrical breakdown, dielectrophoresis, chromatography and ultracentrifugation - and progress towards selective growth of monodisperse samples.
Graphene sheets offer extraordinary electronic, thermal and mechanical properties and are expected to find a variety of applications. A prerequisite for exploiting most proposed applications for graphene is the availability of processable graphene sheets in large quantities. The direct dispersion of hydrophobic graphite or graphene sheets in water without the assistance of dispersing agents has generally been considered to be an insurmountable challenge. Here we report that chemically converted graphene sheets obtained from graphite can readily form stable aqueous colloids through electrostatic stabilization. This discovery has enabled us to develop a facile approach to large-scale production of aqueous graphene dispersions without the need for polymeric or surfactant stabilizers. Our findings make it possible to process graphene materials using low-cost solution processing techniques, opening up enormous opportunities to use this unique carbon nanostructure for many technological applications.
The emergence of graphene nanosheet (GN, 2010 Nobel Prize for Physics) has recently opened up an exciting new field in the science and technology of two-dimensional (2D) nanomaterials with continuously growing academic and technological impetus. GN exhibits unique electronic, optical, magnetic, thermal and mechanical properties arising from its strictly 2D structure and thus has many important technical applications. Actually, GN-based materials have enormous potential to rival or even surpass the performance of carbon nanotube-based counterparts, given that cheap, large-scale production and processing methods for high-quality GN become available. Therefore, the studies on GN in the aspects of chemistry, physical, materials, biology and interdisciplinary science have been in full flow in the past five years. In this critical review, from the viewpoint of chemistry and materials, we will cover recent significant advances in synthesis, molecular engineering, thin film, hybrids, and energy and analytical applications of the "star-material" GN together with discussion on its major challenges and opportunities for future GN research (315 references).
Chemically derived graphene oxide (GO) is an atomically thin sheet of graphite that has traditionally served as a precursor for graphene, but is increasingly attracting chemists for its own characteristics. It is covalently decorated with oxygen-containing functional groups - either on the basal plane or at the edges - so that it contains a mixture of sp(2)- and sp(3)-hybridized carbon atoms. In particular, manipulation of the size, shape and relative fraction of the sp(2)-hybridized domains of GO by reduction chemistry provides opportunities for tailoring its optoelectronic properties. For example, as-synthesized GO is insulating but controlled deoxidation leads to an electrically and optically active material that is transparent and conducting. Furthermore, in contrast to pure graphene, GO is fluorescent over a broad range of wavelengths, owing to its heterogeneous electronic structure. In this Review, we highlight the recent advances in optical properties of chemically derived GO, as well as new physical and biological applications.
Transport properties of progressively reduced graphene oxide (GO) are described. Evolution of the electronic properties reveals that as-synthesized GO undergoes insulator-semiconductor-semi-metal transitions with reduction. The apparent transport gap ranges from 10 ~ 50 meV and approaches zero with extensive reduction. Measurements at varying degrees of reduction reveal that transport in reduced GO occurs via variable-range hopping and further reduction leads to increased number of available hopping sites. Comment: 9 pages, 4 figures
Isolated graphene, a nanometer-thick two-dimensional analog of fullerenes and carbon nanotubes, has recently sparked great excitement in the scientific community given its excellent mechanical and electronic properties. Particularly attractive is the availability of bulk quantities of graphene as both colloidal dispersions and powders, which enables the facile fabrication of many carbon-based materials. The fact that such large amounts of graphene are most easily produced via the reduction of graphene oxide--oxygenated graphene sheets covered with epoxy, hydroxyl, and carboxyl groups--offers tremendous opportunities for access to functionalized graphene-based materials. Both graphene oxide and graphene can be processed into a wide variety of novel materials with distinctly different morphological features, where the carbonaceous nanosheets can serve as either the sole component, as in papers and thin films, or as fillers in polymer and/or inorganic nanocomposites. This Review summarizes techniques for preparing such advanced materials via stable graphene oxide, highly reduced graphene oxide, and graphene dispersions in aqueous and organic media. The excellent mechanical and electronic properties of the resulting materials are highlighted with a forward outlook on their applications.
The nonlinear optical properties of two novel graphene nanohybrid materials covalently functionalized with porphyrin and fullerene were investigated by using the Z-scan technique at 532 nm in the nanosecond and picosecond time scale. Results show that covalently functionalizing graphene with the reverse saturable absorption chromospheres porphyrin and fullerene can enhance the nonlinear optical performance in the nanosecond regime. The covalently linked graphene nanohybrids offer performance superior to that of the individual graphene, porphyrin, and fullerene by combination of a nonlinear mechanism and the photoinduced electron or energy transfer between porphyrin or fullerene moiety and graphene.
Processable, single-layered graphene oxide (GO) is an intriguing nanomaterial with tremendous potential for electronic applications. We spin-coated GO thin-films on quartz and characterized their sheet resistance and optical transparency using different reduction treatments. A thermal graphitization procedure was most effective, producing films with sheet resistances as low as 10(2) -10(3) Omega/square with 80% transmittance for 550 nm light. Our experiments demonstrate solution-processed GO films have potential as transparent electrodes.
Loading of graphite oxide (GO) with tris(2,2'-bipyridyl) iron(II) ions and subsequent calcination affords a novel graphene-based composite with magnetic and electrically conductive properties. The pH of the starting aqueous suspension and the washing procedure play a crucial role in the successful immobilization of the iron precursor, which is mainly governed by ion exchange. The complex is intercalated between the graphene oxide layers, where it adopts a distorted conformation. Rapid heating of this solid results in the deflagration of GO and the formation of ultrafine ( d = 2-14 nm) Fe2O3 particles with maghemite as the dominant phase. The superparamagnetic maghemite crystals are dispersed uniformly in the high-surface-area diamagnetic matrix built up from single or turbostratic stacked graphenes.
A series of novel [60]fullerene-ferrocene and [60]fullerene-porphyrin dyads, in which a fullerene and an electron donating moiety are attached through a flexible triethylene glycol linker are synthesized and their nonlinear optical (NLO) response studied. Specifically, the third-order susceptibility chi(3) of all fullerene derivatives are measured in toluene solutions by the optical Kerr effect (OKE) technique using 532 nm, 35 ps laser pulses and their second hyperpolarizability gamma are determined. All fullerene dyads studied exhibit enhancement of their NLO response compared to pristine fullerenes which has been attributed to the formation of a charge separated state. All experimentally measured hyperpolarizability gamma values are also calculated by the semiempirical methods AM1 and PM3. A good correlation is found between the theoretical and experimental values, suggesting that simple semiempirical methods can be employed for the designing and optimization of the fullerene-containing dyads displaying improved nonlinear responses.
The IWEPNM 2007, International Winter School program, held in Kirchberg, Austria, between March 10-17, 2007, focused on the potential use of zero, one, and two dimensional carbon nanotube systems for various scientific applications. Some of the potential applications include spintronics and quantum electronics, and the replacement of silicon in future electronic devices. Some of the participants from Oxford and Berlin have also displayed the spin of the nitrogen (N) atom that exhibits a low interaction with the environment and can be used for such application. The electronic properties of nanomaterials, with particular emphasis on the experimental results obtained from exfoliated graphene flakes, which demonstrated that charge carriers move like massless Dirac particles in the two-dimensional (2-D) nanocrystal were discussed by another participant.
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