Angle Of Incident Light Research Articles

Dynamic tunable multi-channel ultra-narrowband absorber based on hollowed-out trapezoidal Si–graphene–Au metasurface

Abstract Dynamic tunable metasurfaces are of great interest for their optical modulation properties. This study proposes a metasurface with a rectangular hole etched from a silicon square. By converting this rectangular hole into a trapezoid, we disrupt the symmetry, transforming the symmetry-protected bound states in the continuum (BICs) into a quasi-BIC state, achieving triple Fano resonances with a maximum Q factor of 1074. The results of the multipole analysis suggest resonance modes are toroidal dipole, electric quadrupole and magnetic dipole, respectively. A typical dielectric/dielectric/metal structure is then formed by adding an Au layer below the original structure. The polarized-light absorption of the metasurface is found to be unaffected by the angle of incident light. An analysis of the thickness of the Si is studied on the effect of absorption. Eventually, a single layer of graphene is incorporated at the bottom of the Si. The dynamic modulation of the three absorption peaks of the composite metasurface is achieved by controlling the bias voltage to alter the Fermi level E f of graphene. The Si–graphene–Au structure has a sensitivity of 252.5 nm RIU−1 and the maximum performance value of 126.25 RIU−1 at E f = 1 eV. These results indicate that this composite metasurface has potential applications in the research of sensor direction.

Ultrathin transparent indium tin oxide-based electrodes for enhanced performance of perovskite solar cells

Abstract Perovskite solar cells (PSCs) have been given much attention in photovoltaics-based power generation, particularly in building integrated photovoltaics (BIPV) applications due to their lightweight and promising technical performance. PSCs exhibit remarkable transparency to visible light, which makes them an ideal candidate for BIPV applications such as glass-based solar facades and clear solar windows. As the PSC is yet an immature technology, much research is still required to validate its visibility and cost-effectiveness for different applications including electrical vehicles. This paper takes one step forward in achieving this goal by presenting a new ultrathin transparent electrodes (UTE) design that comprises a square patch layout to improve the performance of transparent conductive materials. The proposed electrode design is aimed to improve the absorption of the material in the ultra-violet (UV) region with high optical transparency. To assess the angular dependence on the absorption characteristics, both transverse magnetic and transverse electric modes are studied at various oblique angles of incident light. Furthermore, interference theory is applied numerically to validate the proposed UTE design. The impact of various geometric parameters including period, ground height, spacer height, and top square resonator length on the performance of the proposed UTE layout is investigated through detailed simulation analysis. Moreover, surface electric field patterns are analyzed to understand the absorption mechanism of the proposed UTE. Results reveal the effectiveness of the proposed structure for various BIPV applications including electric vehicles, wearable electronics, and tandem devices.

Light management in Cu2ZnSnSe4 solar cells with ZnO:Al periodic sub-wavelength architectures

This study used a vacuum deposition technique to manufacture Cu₂ZnSnSe₄ (CZTSe) solar cells, providing a scalable and safe manufacturing approach for low-cost, high-performance photovoltaic technology. Additionally, nanoimprint lithography was successfully employed to fabricate two types of periodic sub-wavelength architectures on the surface of CZTSe solar cells, serving as anti-reflective layers and further enhancing their conversion efficiency. The research demonstrates that when the surface architecture of the CZTSe solar cells is Nano-hill, it exhibits superior gradient refractive index and optimal anti-reflective properties, consistent with simulation results. For CZTSe solar cells with this surface architecture, the average reflectance decreased from the pristine 9.86 %–7.34 %, and at an incident light angle of 60°, the reflectance dropped from 17.99 % to 9.53 %, demonstrating the architecture's omnidirectional anti-reflective capability. The periodic sub-wavelength architectures fabricated in this study enhanced the efficiency of the solar cells from 3.68 % to 6.66 %, not only improving conversion efficiency but also showcasing the potential for comprehensive anti-reflective layers, interface repair, and continuous processing. This research not only contributes to optical design but also holds significant importance for the future development of CZTS(Se) technology.

Composition of Quantum Dot Color Conversion Layer with ZnS Nanoparticle for Facile Ink Formulation and Uniform Inkjet Printing

Quantum dot (QD) is excellent material for next-generation displays because of their superior optical properties, such as high quantum efficiency, narrow full width at half maximum, high color purity, and photoluminescence quantum yield. QD demonstrated efficient absorption of blue light, coupled with high color-conversion efficiency, fabricated them suitable for use as color-conversion layers (CCLs). However, robustness in pixel patterning uniformity and a printing resolution should be further studied. Light emission via conversion through QD films or converter pixels still need to be improved because the blue light can directly transmit the QD layers, sometimes leading to insufficient energy to excite the QDs. Thus, many studies on QD CCLs have focused on improving the absorption and emission properties of QDs, formulating CCL resins with enhanced color conversion efficiency. Scattering can alter the optical path and incident angle of the emitted light to increase internal reflection so that light emission of the optical film can be enhanced for excitation of photons. Thus, light scattering particles, such as titanium dioxide (TiO2), silicon dioxide (SiO2), zinc oxide (ZnO), and zirconium oxide (ZrO2) were carefully tuned to achieve outstanding properties as QD CCLs, increasing color conversion efficiency.In this work, zinc sulfide (ZnS) light diffusers with hydrophobic properties and various size distribution were synthesized. ZnS and QD were mixed in acrylic resin, isobornyl acrylate, with proper composition of initiator and photocrosslinker. The recipe of mixing was considered for a fabrication of QD CCL ink with optimum viscosity, dispersion stability and uniformity, and printability. For the QD-CCL ink with relatively high viscosity, evaluation of jetting profile and pixel-patterning was conducted with commercial ink cartridge, Sapphire QE-256/30AAA (Fujifilm), combined with the custom-built inkjet printer and high-speed camera. With the scale up to 200ppi QD-CCL pattern, the color spectrum, printability, dispersion, optical properties (evaluation of color-emitting image), and surface uniformity were evaluated. Overall, this work will demonstrates the enhanced light converion behavior of QD-CCL layer fabricated by inkjet-printing process and provide a novel evaluation prorocol of uniformity for QD-CCL layer and color conversion device using blue micro-LED.

Ultra-broadband absorber and perfect thermal emitter for high-efficiency solar energy absorption and conversion

This study proposes a pyramid-shaped solar absorber designed with multi-layered Ti-SiO2 ring stacked. The structure achieves an average absorption efficiency of 98.03 % over the range of 280–4000 nm, and under AM1.5 spectral conditions, the weighted average absorption efficiency reaches 97.66 %, the bandwidth with an absorption efficiency greater than 90 % reaches 3750 nm. To explore the reason for achieving ultra-broadband absorption with this structure, the electromagnetic field distribution at three absorption peaks was calculated. The results revealed that the resonance between the polarization direction of the three-layer circular ring stacked structure and the plasmon resonance at the junction of Ti and SiO2 contribute to the model's capability for ultra-broadband high-efficiency absorption. At the same time, the thermal emissivity of the structure was calculated at high temperatures of 1000 K and 2000 K, both exceeding 97 %. Furthermore, due to the fully symmetrical design, the absorber is polarization-independent. It was found through calculations that whether in TM mode or TE mode, as the incident angle varies from 0° to 60°, the average absorption efficiency of the absorber changes only by 11.16 %, thereby verifying the structure's excellent insensitivity to incident light angles. In summary, all these characteristics indicate that the model has excellent application prospects in fields such as solar energy collection and photothermal conversion.

Ultra-wideband terahertz absorber with switchable multiple modes based on graphene and vanadium dioxide metamaterials

This article proposes a dynamic switchable broadband absorber based on graphene and vanadium dioxide (VO2). The temperature could adjust the conductivity of VO2, and external voltage could alter the conductivity of graphene. Therefore, they can be used for broadband absorption that can be switched between low and high frequencies and for achieving coupled ultra-wideband absorption. When the Fermi level of graphene is 0.9e V and VO2 is in a non-metallic state, the absorber can achieve absorption of over 90 % in the range of 2.55 THz-4.86 THz. When the Fermi level of graphene is 0.1e V and VO2 is in a metallic state, the absorber can achieve absorption of over 90 % in the range of 4.30 THz-9.40 THz. When the Fermi level of graphene is 0.6e V and VO2 is in a metallic state, the absorber can achieve absorption of over 90 % in the range of 2.32 THz-9.80 THz. The absorber only partially depends on the incident angle of the incident light, simulation results show that when the incident angle is below 50 degrees, more than 90 % of the absorption bandwidth changes less. The absorber has no relation to the polarization angle of the incident light, and can keep its original property at any polarization angle. This structure has potential applications in electromagnetic wave stealth devices, optical switches and filters.

Review of Angular-Selective Windows with Guest–Host Liquid Crystals for Static Window Applications

This review focuses on the development and advancements in angular-selective smart windows, with particular emphasis on static windows utilizing guest–host liquid crystal (GHLC) systems. Angular-selective windows are designed to adjust their transmittance based on the angle of incident light, offering enhanced energy efficiency and visual comfort in both architectural and automotive applications. By leveraging the anisotropic absorption properties of dichroic dyes, GHLC-based windows can selectively block oblique sunlight while preserving clear visibility from normal viewing angles. Various liquid crystal (LC) alignment configurations, including vertically aligned, homogeneously aligned, hybrid aligned, uniformly lying helix, and twisted aligned LC cells, have been investigated to optimize light control for different installation angles, such as for automotive windshields and building windows. These advancements have demonstrated significant improvements in energy conservation and occupant comfort by reducing cooling demands and regulating sunlight penetration. This review summarizes key findings from recent studies, addresses the limitations of current technologies, and outlines potential future directions for further advancements in smart window technology.

Nanostructures/TiN layer/Al2O3 layer/TiN substrate configuration-based high-performance refractory metasurface solar absorber

Metasurface solar absorber serves as a kind of important component for green energy devices to convert solar electromagnetic waves into thermal energy. In this work, we design a new solar light absorber configuration that incorporates the titanium nitride substrate, aluminum oxide layer, titanium nitride layer, and the topmost refractory nanostructures. The metasurface absorber based on this configuration can achieve an average spectral absorption of over 91% and a total solar radiation absorption of 91.5% at ultra-wide wavelengths of 300–2500 nm. It is discovered that the excellent performance of the proposed metasurface absorber is attributed to the synergistic effects of surface plasmonic effect and Fabry–Pérot (FP) cavity resonance by comprehensive analysis of the simulated field distributions. Furthermore, the effect of geometrical parameter of the proposed configuration on absorber performance is studied, indicating the proposed configuration possesses a large fabrication tolerance. Moreover, the proposed configuration is not sensitive to the polarization direction and the angle of incident light. It is also found that the use of other refractory metal materials and other shapes as the topmost absorbent nanostructures also have good results with this configuration. This work can offer a universal platform for constructing and guiding the design of refractory metasurface solar absorbers.

High Q transparency, strong third harmonic generation, and giant nonlinear chirality driven by toroidal dipole-quasi-BIC

Electromagnetically induced transparency (EIT), nonlinearity, and optical chirality hold significant applications in many areas such as optical switches, slow-light devices, chiral harmonic conversion, and optical storage. In this work, we theoretically propose an asymmetric all-dielectric metasurface supporting toroidal dipole-quasi-bound states in the continuum (TD-q-BICs). High quality (Q) EIT, strong third harmonic generation (THG), and giant nonlinear chirality are achieved via the extremely enhanced electric field energy localized in the Si plate by the TD-q-BIC. A huge transition from high Q EIT with transmission of ∼0.99 to strong chirality with circular dichroism (CD) of ∼0.9 is realized by tuning the angle and polarization state of incident light. Strong THG with efficiency of 4.5 × 10−3 under linear polarization light is due to the highly localized electric field supported by the TD-q-BIC and perfect nonlinear CD chirality with theoretically value of ∼1 originates from the large discrepancy in electric field distributions under different circularly polarized light. Our work provides an innovative paradigm to construct TD-q-BICs-governed EIT analogs, THG, and nonlinear chirality for the development of multifunction nanophotonic meta-devices.

Photonic-Enhanced Perovskite Solar Cells: Tailoring Color and Light Capture.

The current exponential growth of solar electricity technologies toward consumer-oriented applications, as in building- or vehicle-integrated photovoltaics (B/VIPV), is calling for improved solar cells, not only in cost-effectiveness, but also with better adaptability and aesthetics. Here, using perovskite solar cells (PSCs) as test bed, we demonstrate an unprecedented photonic method to generate any color on a cell layout, while also increasing PV efficiency. To this end, photonic surface features were designed for PSCs, which filled the dual purpose of light-trapping (LT) and modulation of reflected light interference. A variety of geometries, from simple gratings to complex semispheroids, were optically optimized for two of the most challenging colors, magenta and green, while assuring the generation of their maximum feasible photocurrent. The best results corresponded to a current density of 22.07 mA/cm2, obtained for the magenta solar cell with top domes, exhibiting an increase of 6.68%, relative to an optimized planar reference cell. In turn, the same type of geometry was able to generate the leading green cell, with up to 21.40 mA/cm2 (a relative increase of 3.44%). Additionally, the uniformity of the optical output of the optimal solar cells was tested under a range of incident light angles, between 0◦ and 60◦, where the current density suffered relative losses only down to 6.65%.

Bending deformation effects on the optoelectronic performance of flexible GaInP/GaAs/InGaAs triple junction solar cells

To achieve genuine carbon neutrality, PV-powered vehicles show promise for future automotive development. However, the impact of curved surfaces on flexible solar cell module performance remains uncertain. This study specifically focuses on newly-designed flexible GaInP/GaAs/InGaAs triple junction solar cells, which have the highest potential output efficiency. A computational model was developed to analyze the electrical performance of curved solar cells, and variations in short-circuit current (Isc) and open-circuit voltage (Voc) with bending angles were determined to closely match experimental data. The effects of incident light intensity, angle, and bending strain on solar cell performance were analyzed to explain the observed Isc and Voc trends. This method can be applied to other III-V group solar cells, providing theoretical support for accurately calculating the performance of curved solar cell modules.

Particle swarm optimization for performance enhancement of cadmium telluride thin film solar cells by embedded nano-grating structures with a plasmonic metal coating layer

As the demand for energy in world is increasing rapidly and there is pursuit for renewable energy sources which is cheap, easy to generate and requires low maintenance, solar energy is a top contender. The world is in dire need of photovoltaic solar cells that can aid in keeping up with the hiking energy demands. However, thin film solar cells (TFSCs) which are developed for cost effectivity, suffer in performance due to reduced thickness. Therefore, this computational study uses Finite-Difference Time-Domain (FDTD) and delves into the scope of using a 1-D nano-grating structure embedded into absorbing layer of cadmium telluride TFSC to enhance the optoelectronic performance. A unique nano-grating structure with SiO2 at its core and aluminium coating aims to enhance the performance of CdTe TFSC with cost effectivity and ease of fabricability as the main motifs. Additionally, an evolutionary computational technique, Particle Swarm Optimization (PSO), was used to determine the optimal parameters of nano-gratings on CdTe TFSCs, i.e., nano-grating height, angle, duty cycle, aluminium coating thickness and grating substrate thickness. The PSO algorithm resulted in a nano-grating structure that yielded an efficiency increase of 52.86% and increase in short-circuit current density of 25.45% with respect to bare CdTe TFSCs. Subsequently, the performance of the optimal nano-grating structure was also observed to be insensitive to variation of wide range of incidence angle of light, a key feature preferred for versatile application of TFSCs.

Comparative Analysis of Two Different MIM Configurations of a Plasmonic Nanoantenna

AbstractTwo plasmonic nanoantenna configurations—nanodisk and nanostrip arrays—in a metal–insulator-metal (MIM) setup were proposed, optimized, and compared by simulating their optical properties in three-dimensional models using COMSOL Multiphysics software. The optical responses, including electric field enhancement, absorption, reflection, and transmission spectra, were systematically investigated. Optimized geometrical parameters led to a significant enhancement of the electric field within the gap layers and almost perfect light absorptance for both structures. The results showed that the enhancement of the electric field depends on the polarization of the incident light. For both polarizations, the periodic circular nanodisk array showed a stronger field enhancement with an electric field enhancement factor of 6.6 × 106 and TE polarization, and a larger absorptance of 98% at its dipole resonance wavelength, indicating the fundamental plasmonic mode. In addition, weaker resonant modes were observed in the absorptance and reflectance spectra of both nanostructures, with the nanostrips exhibiting sharper and stronger higher-order modes, making them suitable for applications requiring precise wavelength selectivity and narrow-band responses. Despite their different geometric shapes, both structures exhibited similar optimized metal film thickness and nanoparticle height, comparable modes in number and position, and identical optimized light incidence angles. Furthermore, increasing the dielectric gap layer thickness and optimizing it to a specific value revealed its ability to measure the refractive index, making it a promising candidate for sensing applications.

Configurable lateral optical forces from twisted mixed-dimensional MoO3 homostructures

Abstract In recent years, the concept of hyperbolic phonon polaritons (HPPs) has revolutionized the field of nanophotonic, enabling unprecedented control over light-matter interactions at the nanoscale. Here, we theoretically propose and study the lateral optical forces in twisted mixed-dimensional MoO3 homostructures. Assisted with the low-symmetry HPPs, we realize a lateral optical force exerted on the Au nanoparticles near the surface of mixed-dimensional MoO3 homostructures with a linear polarized incident light. By controlling the polarization state, incident angle of light and the twisted angle of MoO3, the amplitude and direction of the lateral optical forces can be tailored in the mid-infrared range. Our findings provide a new platform for engineering lateral optical forces to manipulate diverse objects in a flexible and efficient manner.

One dimensional multilayer structure for kerosene adulteration detection in petrol and diesel

Abstract We aim to design a multilayer periodic structure to detect the kerosene adulteration in the petrol and diesel fuels on a single processing setup. We built the structure by arranging TiO2 and SiO2 layers periodically in alternate manner with empty space at the middle. The optical response of the designed structure is then theoretically studied using transfer matrix method. Empty space of the design is filled with different kerosene adulterated petrol and diesel samples for inspecting structure response to incident electromagnetic waves. Theoretical calculations affirm that the proposed structure is capable to detect the fuel adulteration efficiently. Critical performance parameters like sensitivity, quality factor, figure of merit and limit of detection are calculated to check the effectiveness of the sensor. We also optimized the sensitivity of sensors design through modifying the defect thickness as well as angle of incidence of electromagnetic waves, and provides poly fit formula. It is observed that the sensitivity of sensor to detect kerosene adulteration in fuels highly depends on defect thickness and light incidence angle. An efficient sensor possessing high quality factor and figure of merit is realized from the designed structure that is capable of detecting 10 − 5 RIU.

Strong coupling of double excitons with guided mode resonances and quasi-bound states in the continuum in heterogeneous metamaterials.

Heterogeneous metamaterials containing excitonic materials provide an ideal platform for strong exciton-photon coupling. In this Letter, we theoretically demonstrate four strong couplings in a heterogeneous metamaterial consisting of a TiO2 grating standing on a perovskite-WS2-perovskite waveguide layer by tuning the structural sizes. The quasi-bound state in the continuum (qBIC) and the guided mode resonance (GMR) both strongly coupled with the excitons of both perovskite and WS2 under oblique incident illumination, resulting in four large Rabi splittings of 177.32, 187.53, 406.25, and 435.09 meV via a reasonable combination of oscillator strengths of perovskite and WS2. Double strong coupling behaviors are also achieved when the grating period equals 222 nm with an incident light angle of 19.3°. Moreover, double ultrastrong coupling can even be realized by the GMR and qBIC respectively interacting with the exciton of WS2 when its oscillator strength reaches a certain value. Our work paves an effective avenue to realizing strong coupling and even ultrastrong coupling between multiple excitons and multiple optical modes.

Dynamic plasmonic structural color with deep sub-diffraction resolution based on borophene metasurfaces.

Structural colors have seen rapid development in recent years, yet two-dimensional (2D) materials have seldom taken center stage as pixel materials. In this study, we propose a novel approach utilizing the emerging 2D material borophene, wherein resulting metasurfaces can generate plasmonic structural colors with tunability and ultra-high resolution. Numerical investigations demonstrate that borophene metasurfaces support visible localized surface plasmon resonances at deep subwavelength scales under linear-polarized light excitation, thus enabling the realization of structural colors with an unparalleled resolution of up to 106 dots per inch (dpi)-an advancement of one order of magnitude over conventional counterparts. Furthermore, by modulating the electron density of borophene, these structural colors can be dynamically tuned across a broad spectrum. We highlight their high robustness against incident light angles and explore the influence of periodicity and polarization angle on color rendition. Finally, we present their potential applications in optical anti-counterfeiting, encryption, and switchable imaging methodologies. This work may promise future advancements in ultracompact, tunable, and lightweight display technologies.

Development of single-sided structure collimation film for direct-lit collimated backlight module.

In this paper, we proposed an optical structure to enhance the collimation and uniformity of 405 nm LED backlight modules. The structure is called a single-sided structure collimation film (SSSCF), which consists of a lenticular lens array, slit apertures, and a highly reflective coating surface. A lenticular lens array with slit apertures converts the angle of diffusive incident light into collimated light. The high-reflective coating of the collimation film can reflect back the light that does not enter the slit aperture to the backlight module for energy recycling. Finally, we have developed a direct-lit backlight module with optimized collimation properties (FWHM = ±3.4°, gain = 2.3%, NSR = 0) and great uniformity (uniformity > 83.5%). We also demonstrated good consistency between our simulation results with optical measurement. The collimated backlight module developed in this study has great potential for future applications, including high-precision 3D printing objects, liquid crystal displays with high contrast ratio or narrow viewing angles, and telecentric illumination devices used in precision machine vision systems.

Kretschmann configuration as a method to enhance optical absorption in two-dimensional graphene-like semiconductors

Objectives. The optical properties of two-dimensional semiconductor materials, specifically monolayered transition metal dichalcogenides, present new horizons in the field of nano- and optoelectronics. However, their practical application is hindered by the issue of low light absorption. When working with such thin structures, it is essential to consider numerous complex factors, such as resonance and plasmonic effects which can influence absorption efficiency. The aim of this study is the optimization of light absorption in a two-dimensional semiconductor in the Kretschmann configuration for future use in optoelectronic devices, considering the aforementioned phenomena. Methods. A numerical modeling method was applied using the finite element method for solving Maxwell’s equations. A parametric analysis was conducted focusing on three parameters: angle of light incidence, metallic layer thickness, and semiconductor layer thickness.Results. Parameters were identified at which the maximum area of absorption peak was observed, including the metallic layer thickness and angle of light incidence. Based on the resulting graphs, optimal parameters were determined, in order to achieve the highest absorption percentages in the two-dimensional semiconductor film.Conclusions. Based on numerical studies, it can be asserted that the optimal parameters for maximum absorption in the monolayer film are: Ag thickness <20 nm and angle of light incidence between 55° and 85°. The maximum absorption in the two-dimensional film was found only to account for a portion of the total absorption of the entire structure. Thus, a customized approach to parameter selection is necessary, in order to achieve maximum efficiency in certain optoelectronic applications.

Long‐Infrared Broadband Polarization‐Sensitive Absorber with Metasurface Based on Ladder Network

AbstractPlasmonic resonant and metamaterial structures allow for manipulating the polarization properties of electromagnetic waves to achieve polarization beam splitting. Broadband polarization‐sensitive metamaterial absorbers based on surface plasmon polaritons have the advantages of high‐energy utilization and excellent stability, which may replace traditional polarizing devices. Here, an absorber based on a ladder network construction is designed theoretically and investigated experimentally. The absorber can possess almost 92% average absorptivity for TM polarization light in 8–12 µm range (experimental result: 83% from 7 to 11 µm). It is especially sensitive to the polarization angle of incident light, and with the increase of polarization angle, the broadband absorption response can present analogously monotonous reduction. The theoretical and experimental results for TE polarization light are 12% and 25%, respectively. The broadband absorption response performs angle insensitive property under oblique incidence. The proposed metamaterial absorber opens a path to realize broadband polarization‐sensitive absorption based on simple nanostructure. It will possess great potential applications in high‐performance polarimetric photodetectors and imaging fields.