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The optical properties of Parylene C film in the mid-infrared region from 2.0 μm to 10.0 μm. (a) The absorption spectrum measured by FTIR spectrometry of Parylene C film with a thickness of less than 0.80 μm. The repeating unit of the Parylene C polymer is shown in the inset. Three measurements were repeated for Parylene C films with slightly different thicknesses. The obvious strong absorption bands correspond to the vibrational stretches of C-H at approximately 3.29 μm (3031.8 cm−1), C = C at 6.89 μm (1450.3 cm−1) and C-Cl at 9.57 μm (1044.9 cm−1). (b) The optical constant was measured by spectroscopic ellipsometry (IR-VASE®, J.A. Woollam). The permittivity of Parylene C contains a nondispersive component in the refractive index.
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Surface-enhanced infrared absorption spectroscopy has attracted increased attention for direct access to molecular vibrational fingerprints in the mid-infrared. Perfect-absorber metamaterials (PAMs) with multi-band spectral responses and significant enhancement of the local near-field intensity were developed to improve the intrinsic absorption cro...
Citations
... Plasmonic nanostructures with tunable optical properties have many applications in the field of nanophotonics and optoelectronics for applications in sensitive and labelfree biological sensing of various molecular compounds [1][2][3][4]. Important implications can be found in medical research [5,6] but also for environmental monitoring [7] and spectroscopy [8,9]. The excitation of the surface plasmonic (SP) modes leads to a strong concentration of light energy in nanoscale volumes and, in parallel, increases the intensity of the near optical field by several orders of magnitude with respect to exciting field. ...
Arrays of metal nano-holes have proved to be among of the most promising structures for applications in the field of nano-photonics and optoelectronics. Supporting both localized and propagating surface plasmons resonances, they are characterized by very high versatility thanks to the tunability of these modes, by means of the change of their periodicity, the size of the holes and metal composition. The interaction between different optical features can be exploited to modulate electromagnetic field distribution leading various hot-spots excitations on the metal surfaces. In this work, long range ordered arrays of nano-holes in thin gold films, with different geometrical characteristics, were fabricated by a modified nano-sphere lithography protocol, which allows precise control on holes’ dimensions together with the preservation of the order and of the pristine periodicity of the array. An in-depth analysis of the correlation between surface plasmon modes interference and its effect on electromagnetic field distribution is proposed, both by numerical simulations and experimentally. Finally, metal nano-holes arrays are exploited for surface enhanced Raman experiments, evaluating and comparing their performances by the estimation of the enhancement factor. Values close to the single molecule detection are obtained for most of the samples, proving their potentialities in surface enhanced spectroscopy applications.
... Sandwich structures with a metal nanoantenna-insulator-metal film (MIM) configuration is a common design in previous metamaterial absorbers, where one can tune the resonance wavelengths of the perfect absorbers by changing the size or shape of the top nanoantennas as well as the thickness of the middle dielectric spacer layer [18][19][20][21][22][23][24][25][26][27]. Due to the inherent Ohmic losses in metals, MIM-based MPAs often exhibit low quality resonances with a relatively broad bandwidth (>40 nm), which is far from the desired performance in spectroscopy and biosensing fields [28][29][30][31]. ...
Metamaterial perfect absorbers (MPAs) are attractive platforms for the unique manipulation of electromagnetic waves from near-field to far-field. Narrow-band MPAs are particularly intriguing for their potential applications as thermal emitters or biosensors. In this work, we proposed ultra-narrow-band MPAs based on surface lattice resonance (SLR) modes of WS2 nanodisk arrays on gold films. The SLR modes stem from the coupling between the magnetic dipole modes of individual nanodisks and the Rayleigh anomaly of the array giving rise to high quality-factor resonances. With proper design of the nanodisk array, an ultra-narrow-band of 15 nm is achieved in the near infrared wavelength range. The underneath gold film provides the loss channel converting the incident light within the narrow band into heat in the gold film, effectively creating a perfect absorber. Systematic numerical simulations were performed to investigate the effects of the geometrical parameters on their optical properties, demonstrating the great tunability of this type of MPAs as well as their potential for engineering light-matter interactions.
... These novel metasurfaces have not only been considered for chirality study but also for other optical and opto-electronic applications [27][28][29][30][31][32][33]. For example, plasmonic metamaterial perfect absorbers have huge implications in thermal detection and imaging, tera-Hertz (THz) spectroscopy, selective spectral filtering, refractive index sensing, and chemical sensing [34][35][36][37][38][39][40][41][42][43][44][45][46][47]. Often, these devices are designed to be polarization sensitive or insensitive. ...
A multifunction plasmonic metasurface made of metal-dielectric-metal (MDM) layers is designed, and its chiral, absorption, and refractive index sensing properties are studied numerically using finite difference time domain (FDTD) computation. Top layer of the proposed novel metasurface consists of four L-shape gold strips arranged in a specific orientational sequence into a square unit cell whose period (along X direction and Y direction) is varied from 800 to 1400 nm in a step of 200 nm. The proposed super-structure shows highly chiral behaviour with multi bands circular dichroism (CD) between ~ 600 and 1200 nm with highest CD value of about 0.4. The CD spectral response is seen to be tunable with the structural parameters such as periods and appropriate L-strip length. True chiral nature of the proposed structure is cross-checked by computing its enantiomer that shows a mirror reflection of CD response of the original structure. Multi-work functionalities are investigated by studying perfect absorption and refractive index sensing properties of the metasurface. The study shows polarization independent multi-resonance spectral absorption that reaches to ~ 100% in some cases. On the other hand, refractive index sensing study shows high sensitivity (S) of 700–750 nm/RIU (per refractive index unit) with figure of merit (FOM) of 5–10. Owing to its exotic optical properties, the novel metasurface may be considered for chip level integration for multi-purpose work functionalities.
... Finally, a continuous sheet metal layer is always selected as the bottom layer to eliminate transmission of electromagnetic waves. This is because the penetration depth is lower than the thickness of the bottom layer [7,8]. Since different structural design strategies are adopted, the reported absorbers exhibit a variety of performances, including single-band metamaterial absorber [9], dual-band metamaterial absorber [10,11], or multi-band metamaterial absorber [12,13]. ...
A metamaterial-based absorber with metal–dielectric–metal (MDM) structure design strategy is proposed and verified in terahertz the band. An absorption peak (amplitude is 92%) is obtained at the resonance frequency point 4.2 THz. Simulation results show that this absorption peak originates from the resonance of localized surface plasmon modes. The measured FWHM of this absorption peak is 0.07 THz, and the quality factor Q is 60. In the first sets of experiments, the lattice constant P is reduced from 8 to 6 μm, which leads to this absorption amplitude enhance from 92 to 97.4%, and the resonance frequency point move from 4.2 to 4.08 THz. Similarly, when the diameter D is increased in the second sets of experiments, the absorption amplitude is also enhanced. In the third set of experiments, samples are covered with different liquid layers (acetonitrile, acetone, methanol, or benzene layers). Four measured maximum absorption values are achieved: 97%, 98%, 99%, and 99.4%, respectively. The resonance frequency point is also moved to lower frequency point. The feasibility of this absorber for liquid refractive index sensing is proven. In the fourth groups of experiments, samples are covered with an ethanol layer or a chloroform layer; the absorption peaks are both reduced and moved to higher frequency points with the measured temperature increasing. The feasibility of this absorber for temperature sensing is also verified.
... The cross resonator is considered an electric ring resonator (ERR) 26 that is able to strongly manipulate the incident IR radiations. The major and minor axes of the designed CEs control the electric response while the magnetic response is tuned by the thickness of the dielectric layer 27 . The resonant frequency of a regular cross resonator, i.e. crossed rectangles, can be estimated from the microwave regime using the formula 28 : ...
... layered MIM structure usually provides two bands of absorption. One of these bands is attributed to the propagation of surface plasmon polaritons (SPPs) while the other is related to MPs and occurs at longer wavelengths 27 . The SPPs are excited at the interface between the top resonator and the dielectric layer while MPs arise from the coupling mechanism between the incident IR radiations and magnetic resonances inside the absorber 23 . ...
We propose a wide-band metamaterial perfect absorber (MPA), using the coupling in the near-field of a quadruple split-ring resonator concentric with crossed ellipses. We designed the MPA with a metal-insulator-metal (MIM) structure for use in thermal energy harvesting. A gradient-based optimization approach was carried out to maximize the absorption of infrared (IR) radiation around 10 μm. Owing to the near-field coupling of resonators with optimal design parameters, the peaks of the absorption responses approach each other, thus broadening the overall bandwidth with almost unity absorptivity. The proposed design has a resonance at 10 μm resulting from magnetic polaritons (MPs) and thus maintains high absorption above 99% up to a range of incident-angles greater than 60° and exhibits a polarization-free behavior due to symmetry. When the optimal design was numerically examined to fabrication tolerances, it showed negligible sensitivities in the absorptivity with respect to design parameters. The strong electric field enhancement inside the split-ring gaps and between the ends of the cross arms and the surrounding ring enables designing MIM diodes to rectify the harvested thermal radiations at 288 K. MIM diodes can be built by the deposition of thin insulators to sit in these gaps. The MIM diode and MPA work together to harvest and rectify the incident IR radiation in a manner similar to the operation of rectennas. The MPA outperforms the traditional nano-antennas in impedance matching efficiency because of its higher resistance. Also, its dual-polarization reception capability doubles the rectenna efficiency. Our proposed MPA retained absorptivity more than 99% when coupled with MIM diodes whose resistances are in the range of 500 Ω-1 MΩ.
... The wide range of applications for energy processing, sensing and photocatalysis is a source of researchers 'great interest in perfect absorption (Wang et al. 2020;Wu et al. 2020;Yi et al. 2019). Surfaces with adjustable optical properties, including applications such as (Adato et al. 2009;Wu et al. 2011;Li et al. 2013;Chen et al. 2015) controlled light absorption (Ogawa et al. 2015) and color printing, have been extensively studied and are of interest for sensing (Tan et al. 2014;James et al. 2016;Miyata et al. 2016). Landy et al. (2008) initially developed the PPA to match the impedance response to the environmental medium with both electric and magnetic plasmon arousing resonances. ...
Frequency-selective heat infrared (IR) detectors are promising for numerous new apps such as solar cell detection, gas analysis, multi-color imaging, multi-channel detector, recognition of artificial objects in a natural setting, but these features involve extra filters which lead to elevated costs. Plasmonic metamaterial absorbers (PMAs) can impart frequency selectivity to standard heat, IR detectors merely by regulating the absorber surface geometry to generate surface plasmon resonance at the desired frequency. We present a nanoantenna-based mid-infrared absorber for heat infrared detectors. Our structure uses a portion of the noble metal used in standard absorbers and is only one layer thick, which enables incredibly tiny thermal conductivity leading to possibly very low thermal detector noise. Simulation results show that the proposed nanoantennas can achieve a harvesting efficiency of 40% at a frequency of 150 THz where the antenna input impedance is matched to that of fabricated rectifying devices. Achieve maximum bandwidth Absorber from 100 THz to 200 THz for application purposes energy harvesting sensor.
... Sub-wavelength absorbers have attracted considerable attentions due to their light and thin features which enable their wide applications ranging from biochemical sensing [1,2], and enhanced spectroscopies to solar cells [3][4][5]. Classical metal-insulator-metal (MIM) absorbers consist of top-layer metallic resonators and a bottom metal mirror separated by a spacer layer. ...
Optical absorbers have received a significant amount of attention due to their wide range of applications in biomedical sensing, solar cell, photon detection, and surface-enhanced Raman spectroscopy. However, most of the optical absorbers are fabricated with high-cost sophisticated nanofabrication techniques, which limit their practical applications. Here, we introduce a cost-effective method to fabricate an optical absorber by using a simple evaporation technique. The absorbers are composed of evaporated nanoparticles above a silver (Ag) mirror separated by a silicon oxide layer. Experimental results show over 77% absorption in the wavelength range from 470 to 1000 nm for the absorber with isolated Ag nanoparticles on the top. The performance of the absorber is adjustable with the morphology and composition of the top-layer nanoparticles. When the top layer was hybrid silver-copper (Ag-Cu) nanoparticles (NPs), the absorption exceeding 90% of the range of 495–562 nm (bandwidth of 67 nm) was obtained. In addition, the bandwidth for over 90% absorption of the Ag-Cu NP absorber was broadened to about 500 nm (506–1000 nm) when it annealed at certain temperatures. Our work provides a simple way to make a highly efficient absorber of a large area for the visible light, and to transit absorption from a narrow band to broadband only by temperature treatment.
... A high-performance light absorber is one of the most studied topics in nanophotonics, leading to different attempts to devise perfect light absorbers, operating either in narrowband or broadband frequency regimes, by using various materials and structures. Perfect absorbers have a variety of applications in research areas such as sensing [1], Mahmut Can Soydan soydan@ee.bilkent.edu.tr 1 spectroscopy [2], photovoltaic [3] and thermal photovoltaic [4], and solar vapor generation as well as photodetection [5]. Metamaterials, with their exceptional properties that cannot be observed in nature, are of great use for the purpose of designing the optimum perfect absorber. ...
In this paper, we scrutinize unprecedented potential of transition metal carbides (TMCs) and nitrides (TMNs) for realization of light perfect absorption in an ultra-broad frequency range encompassing all of the visible (Vis) and near infrared (NIR) regions. For this purpose, two different configurations which are planar and trapezoidal array are employed. To gain insight on the condition for light perfect absorption, a systematic modeling approach based on transfer matrix method (TMM) is firstly utilized. Our modeling findings prove that the permittivity data of these TMCs and TMNs are closely matched with the ideal data. Thus, they can have stronger and broader absorption behavior compared to metals. Besides, these ceramic materials are preferred to metals due to the fact that they have better thermal properties and higher durability against erosion and oxidation than metals. This could provide the opportunity for design of highly efficient light harvesting systems with long-term stability. Numerical simulations are conducted to optimize the device optical performance for each of the proposed carbides and nitrides. Our findings reveal that these ceramic coatings have the broadest absorption response compared to all lossy and plasmonic metals. In planar configuration, titanium carbide (TiC) has the largest absorption bandwidth (BW) where an absorption above 0.9 is retained over a broad wavelength range of 405–1495 nm. In trapezoid architecture, vanadium nitride (VN) shows the widest BW covering a range from 300 to 2500 nm. The results of this study can serve as a beacon for the design of future high-performance energy conversion devices including solar vapor generation and thermal photovoltaics where both optical and thermal requirements can be satisfied.
... In many applications especially in the fields such as thermal radiation tailoring 1 , sensitive detection 2,3 , and sensing 4,5 , narrowband light absorption enhancement is particularly desirable. In the past decade, hybrid metal/dielectric systems such as the metal-dielectric-metal (MIM) sandwich structures have been intensively investigated due to the nearly-perfect absorption or perfect absorption performances [6][7][8][9][10][11][12][13][14][15][16][17][18] . These MIM structures usually consist of periodically arranged metal patches and a metallic substrate separated by a dielectric layer, the electric resonance can be generated by the metal patches and the magnetic resonance can be produced by the anti-parallel currents in the top and bottom metal layers 6 . ...
The effect of ultra-narrowband light absorption enhancement is presented by using metamaterials with symmetry-broken square silicon patches (SSPs). The symmetry of the SSP can be broken by introducing a narrow slit deviating from its center. By breaking the symmetry of the SSPs, slit resonance mode with standing wave patterns can be excited, and the locations of the absorption peaks can be well estimated by using the Fabry-Pérot (F-P) cavity model. Although there is no excitation of surface plasmon resonance, ultra-narrowband light absorption can be achieved by minimizing the reflectance through perfect impedance matching and simultaneously eliminating the transmittance by the metallic substrate. Good ultra-narrowband absorption features can be maintained as the parameters of the buffer layer and the SSPs are altered. When this type of symmetry-broken SSPs-based metamaterial is used in refractive-index sensors, it shows excellent sensing properties due to its stable ultra-narrowband absorption enhancement.
... The FDTD examination of SERS on fabricated Au nanostructures as a result of LSPR yielded an interesting result [30]. Researchers have revealed so many attractive features of plasmonic metamaterials in connection with LSPR and some expectations from their ability to transmit light [31][32][33][34][35] and the plasmonic sensors [36][37][38][39][40][41][42][43]. This progress was remarkable because of their electromagnetic features. ...
Plasmonic nanoparticles of noble metals, mostly
gold (Au), show surface plasmon resonance features within
the vicinities of visible and near-infrared spectrum, and its
plasmonic techniques emerge from the cooperative oscillations
of free electrons controlled by the electromagnetic
field influence of the incident light within the region. This
work aims at producing reduced cost surface-enhanced
Raman spectroscopy (SERS) enhancement factor of gold
nanoparticle (AuNP) using the finite-difference time-domain
method. The result shows that for the selected three
types of substrates of SiO2, Ge, and Al2O3, the SERS
effects of Ag on SiO2[Ge[Al2O3 agree with the
enhancement order (i.e., SiO2[Ge[Al2O3) from the
previous experiment of Yang et al. (Appl Surf Sci
436:367–372, 2018). Due to the limitation of the semiconductor’s
substrates, in subsequence simulations, Al
substrate was used instead. Further simulations reveal that
the intensity of Ag on Al substrate is greater than that of
SiO2, Ge, and Al2O3 semiconductor substrates. In like
manner, the simulation also gave a greater enhancement
with AuNP/Al substrate. (The localized electric field
enhancement effect of AuNP/Al substrate has more signal
than the previous.) The results obtained from the consideration
of different diameters of the Au sphere and the
interparticle spacing for some specified range of numbers
under consideration have enlarged the comprehension of
SERS substrates. The operation (mechanism) of the
wavelength’s arousal is a function of the particle’s
structure, miniaturization, and substrate type for the SERS
effect.
