Giuseppe Calafiore's research while affiliated with Lawrence Berkeley National Laboratory and other places

Publications (35)

Article
Full-text available
Spin-polarized directive coupling of light associated with the photonic quantum spin-Hall effect (QSHE) is a nanoscale phenomenon based on strong spin–orbit interaction that has recently attracted significant attention. Herein, we discuss the experimental manifestation of QSHE intrinsic in the Bloch waves associated with a bound state in the contin...
Article
Full-text available
Materials for nanophotonic devices ideally combine ease of deposition, very high refractive index, and facile pattern formation through lithographic templating and/or etching. In this work, we present a scalable method for producing high refractive index WS2 layers by chemical conversion of WO3 synthesized via atomic layer deposition (ALD). These c...
Article
Full-text available
Plasmonic substrates play a crucial role in the confinement and manipulation of localized electromagnetic fields at the nanoscale. The large electromagnetic field enhancement at metal/dielectric interfaces is widely exploited in surface-enhanced fluorescence (SEF) and surface-enhanced Raman scattering (SERS) spectroscopies. Despite the advantage of...
Article
Plasmonic bowtie nanoantennas are intriguing nanostructures, capable to achieve very high local electromagnetic (EM) field confinement and enhancement in the hot spots. This effect is strongly dependent on the gap size, which in turn is related to technological limitations. Ultra-narrow gap bowtie nanoantennas, operating at visible frequencies, can...
Article
Full-text available
The realization of an efficient optical sensor based on a photonic crystal metasurface supporting bound states in the continuum is reported. Liquids with different refractive indices, ranging from 1.4000 to 1.4480, are infiltrated in a microfluidic chamber bonded to the sensing dielectric metasurface. A bulk liquid sensitivity of 178 nm/RIU is achi...
Article
Full-text available
New sources of clean water are currently being researched and implemented, to face global water shortage. Techniques such as desalination or cloud seeding can have a high yield but present problems such as excessive energy consumption or consistent environmental impacts. Fog harvesting stands out for being considerably simpler and inexpensive compa...
Article
Full-text available
Fog harvesting stands out as a simple and inexpensive form to produce drinkable water from alternative sources, when compared to other available techniques. This paper presents results from a set of experiments performed on radiative condensers, deemed as a promising system to be integrated in building envelopes, following a literature review on fo...
Conference Paper
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Fabricating photonic structures directly on the edge of an optical fiber opens opportunities in telecommunication, sensing, lab-on-fiber and as a replacement for the conventional free-space optics. The main advantages are long-term stability, compact size, ease of use, and the scalability. We report a novel method to fabricate 3D free-form photonic...
Article
Full-text available
Fano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering...
Article
The discovery of the topological nature of free-space light and its quantum chiral behavior has recently raised large attention. This important scientific endeavor features spin-based integrated quantum technologies. Herein, we discuss a novel phenomenon based on a resonantly-enhanced quantum spin-Hall transport of light observed in a dielectric re...
Article
Full-text available
One of the major challenges to the widespread adoption of plasmonic and nano-optical devices in real-life applications is the difficulty to mass-fabricate nano-optical antennas in parallel and reproducible fashion, and the capability to precisely place nanoantennas into devices with nanometer-scale precision. In this study, we present a solution to...
Poster
Full-text available
Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. Here we report on the fabricatio...
Article
Full-text available
In this Letter we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.69),...
Preprint
Full-text available
In this Letter we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.69),...
Article
This roadmap, through the contributions of ten groups worldwide, contains different techniques, methods and materials devoted to sensing in nanomedicine. Optics is used in different ways in the detection schemes. Raman, fluorescence and infrared spectroscopies, plasmonics, second harmonic generation and optical tweezers are all used in applications...
Article
Full-text available
Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. In this paper we report the fabr...
Preprint
Full-text available
Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. In this paper we report the fabr...
Article
Nanoimprint lithography (NIL) of functional high-refractive index materials has proved to be a powerful candidate for the inexpensive manufacturing of high-resolution photonic devices. In this paper, we demonstrate the fabrication of printable photonic crystals (PhCs) with high refractive index working in the visible wavelengths. The PhCs are repli...
Article
Full-text available
We present a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) one-dimensional sequences and two-dimensional arrays as an effective method for spectral characterization in the spatial frequency domain of a broad variety of metrology instrumentation, including interferometric microscopes, scatterometers, phase...
Article
Any metrology tool is only as good as it is calibrated. The characterization of metrology systems requires test patterns at a scale about ten times smaller than the measured features. The fabrication of patterns with linewidths down to 1.5 nm is described. The test sample was designed in such a way that the distribution of linewidths appears to be...
Article
A step-and-repeat nanoimprint lithography (SR-NIL) process on a pre-spin-coated film is employed for the fabrication of an integrated optical device for on-chip spectroscopy. The complex device geometry has a footprint of about 3 cm2 and comprises several integrated optical components with different pattern size and density. Here, a new resist form...
Article
Full-text available
This Letter presents the design and experimental results for an on-chip photonic device for laser spectrum monitoring that combines a nanospectrometer and an array of Young’s interferometers. The array of Young’s interferometers and the spectrometer measure the width and wavelength of a spectrum in visible light, respectively. The accuracy of spect...
Article
Full-text available
Computer-generated planar holograms are a powerful approach for designing planar lightwave circuits with unique properties. Digital planar holograms in particular can encode any optical transfer function with high customizability and is compatible with semiconductor lithography techniques and nanoimprint lithography. Here, we demonstrate that the i...
Article
Numerous studies report the importance of nanoscale metallic features to increase the sensitivity of gas sensors, biodetectors, and for the fabrication of the new-generation plasmonic devices. So far, nanoimprint lithography has not shown the capability to pattern a metallic structure that would both be sub-15 nm and sufficiently thick to ensure el...
Article
We report a novel nanofabrication method to fabricate printable integrated circuits with a high refractive index working in the visible wavelength range. The printable planar ligthwave circuits are directly imprinted by ultra-violet nanoimprinting into functional TiO2-based resist on the top of planar waveguide core films. The printed photonic circ...
Article
A strategy for fabricating nanoimprint templates with sub-10 nm line and 20 nm pitch gratings is demonstrated, by combining electron beam lithography and atomic layer deposition. This is achieved through pitch division using a spacer double-patterning technique. The nanostructures are then replicated using step-and-repeat ultra-violet assisted nano...
Article
A novel and robust route for high-throughput, high-performance nanophotonics-based direct imprint of high refractive index and low visible wavelength absorption materials is presented. Sub-10 nm TiO(2) nanostructures are fabricated by low-pressure UV-imprinting of an organic-inorganic resist material. Post-imprint thermal annealing allows optical p...

Citations

... In principle, BIC is also a unique phenomenon of non-Hermitian system around Exceptional points (EPs). Considering the ultrahigh-Q factors and preserved symmetries, the potential impacts of symmetry-protected BICs [39] on superchiral fields are highly desirable but less studied yet. Herein, we employ the physics of merged BICs with orthogonal polarizations [31,40] to construct superchiral field and explore its significance on chiral light-matter interactions. ...
... g/cm 3 ), which they attributed in part to ligand incorporation. WO 3 films were also deposited using BTBAW and O 2 plasma at 40 and 300°C by Chen et al. 29 31 Oxygen vacancy content in WO 3 , assessed using x-ray photoelectron spectroscopy (XPS), was found to decrease with increasing O 2 partial pressure. Finally, a recent ALD study using BTBAW and various co-reactants at 350°C revealed that using stronger oxidizers, such as NO 2 or O 3 when compared to H 2 O, O 2 , or H 2 O 2 /H 2 O, more effectively cleaved W-N bonds and resulted in a lower impurity content. ...
... (b) schematic diagram of multipole radiation in periodic structure, and (c) multipole interaction mechanism of symmetry-protected BIC and accidental BIC [107] 第 1 期 姚建铨, 等: 周期光学系统中的连续域束缚态 before and after the merger, where the Q factor of the merged quasi-BIC is always greater than that of isolated quasi-BIC [119] ; (c) schematic diagram for the structure and function of dynamic BICs based on photo-doped rectangular and cylindrical silicon [123] © 2019 Optical Society of America; (d) a patterned graphene-metal metasurface device by tuning the graphene Fermi-energy level realizes dynamic switching between BIC and quasi-BIC [68] ,且 检测极限低 [125][126][127] has narrow transmission peaks in the low background transmittance, and realizes the function of spatial narrow-band filtering [71] ; (b) high-sensitive molecular sensor based on all dielectric tetramer supporting quasi-BIC [68] 第 1 期 姚建铨, 等: 周期光学系统中的连续域束缚态 图 10 (a~b)BIC分子光谱编码等像基应用 [65] ;(c~d)展示BIC在非线性领域的应用,这里(c)为用于产生倍频光的T字准 BIC器件,(d)为三次谐波和二次谐波强度与普通器件的效果对比 [130] ;(e)产生微激光的准BIC超表面的泵浦功率 与激光输出功率的关系,及其(f)周期尺寸和激光波长对应关系 [119] Fig. 10 (a~b) Applications of BICs based on molecular spectral coding [65] . (c~d) The non-linear applications of BICs, where (c) shows a T-shaped quasi-BIC device for generating frequency doubling light, and (d) show the comparison of the third harmonic and second harmonic intensities with those of ordinary devices [130] . ...
... 1,2 Because of the high transparency and high work function, MoO x can be used as a hole extraction layer in silicon heterojunction solar cells, [3][4][5][6] as anode buffer layer in organic photovoltaics 7 , or as anode interface on indium thin oxide to improve the stability of organic light emitting diodes. 8 Other applications include, but are not limited to, solid-state lithium ion batteries, 9 plasmonics, 10 as alternative material to the metallic counterpart, [11][12][13][14] photochromic and thermochromic devices, 15 pseudocapacitors, 16 since thin films of molybdenum oxide exhibit high capacity, low electrical resistivity, high thermal and chemical stability. Molybdenum oxide has also demonstrated good catalytic properties for applications in nanostructured gas sensors. ...
... Maksimov's work has proved that the refractive index sensing with optical bounds states in the continuum can be implemented in dielectric structures [7]. The feasibility of good performance of refractive index sensors driven by BIC in experiments has also been demonstrated in recent work [8]. ...
... Water harvesting from fog using building envelops, the journal has provided the best practice of atmospheric water harvesting method by carried out experimental and analysis. There are three types of fog harvesting systems which are mesh collector system, chemical fog collector and flat fog condenser; experiment with the three types of systems has been carried in South America, Middle East Countries, South Africa and India (Caldas et al. [4]). ...
... Biomimetic and biomimicry approaches have demonstrated suitability to adapt to water stimuli for responsive building envelopes. Plant leaves and some invertebrates show the most efficient and developed known systems for water harvesting, in some cases as a coping mechanism to water scarcity in their regular environment and as a means to secure fresh water [71,72]. However, their surface textures tend to be textured and heterogeneous, leading to a wettability behavior that could be described either by a Wenzel state, in which the surface is completely wet, leading to a hydrophilic surface, or by a Cassie-Baxter state, in which the drop sits on the surface, but there is trapped air between the asperities, leading to a hydrophobic surface [69,73,74]. ...
... In another article the same authors reported the NIL-enabled realization of a 3D beam splitter for light manipulation, together with other 3D photonic structures directly onto the termination of the fiber. The same group has also provided examples of a highrefractive-index Fresnel lensed fiber, a vortex phase plate, and a beam shaper in Munechika et al. (2018). ...
... This is in turn important for two reasons mainly: Fabrication uncertainties or tolerances, which will result in non-perfectly identical devices; and dynamic range, since from the moment that events start to happen to a particular resonator in the system, symmetry will be broken. Many interesting systems have been presented even with this limitation being present: Arrays of many resonators with small (Stassi et al., 2017;Stassi et al., 2019) or large coupling (Marquez et al., 2017); mass sensors (Thiruvenkatanathan et al., 2010a;Wang et al., 2018), electrometers (Thiruvenkatanathan et al., 2010b), accelerometers (Pandit et al., 2019;Wang et al., 2020;Zhang et al., 2020;Zhang et al., 2021), etc. ...
... A selection of achievements of this field, sometimes referred to as to "lab-on-fiber," [2][3][4][5] includes metalens-based device and diffractive optical elements for light focusing, 6-8 light conversion, 9,10 optical trapping, 11 holography, 12 and plasmonic structures or arrays of nanoelements for surface-enhanced spectroscopy and sensing. 4,13,14 The first successful experiments on boosting coupling efficiencies at selected angles of incidence through fiber-interfaced nanostructures used arrays of plasmonic nanodots located on SMF-28. 15,16 This arrangement enhances the coupling efficiencies up to angles of 80 through opening an additional diffraction channel, outperforming the original SMFs by orders of magnitude. ...