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Selective Absorption of Photonic Crystal with Graphene
摘要： Selective absorption of photonic crystal with graphene is studied. The Photonic Crystal at THz regime with permittivity 4.2 is designed and validated with rigorous coupled-wave analysis method (RCWA) and finite element method (FEM). The selective absorption is achieved by combining the Photonic Crystal with Graphene. The selective absorption is explained with Fano resonance fitting method.
关键词： RCWA,FEM,THz,Selective absorption,Photonic crystal (PC),Graphene
更新于2025-09-16 10:30:52
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Metal Oxide Grating based Plasmonic Refractive Index Sensor with Si layer in Optical Communication Band
摘要： Nanostructure based devices are crucial for many applications including surface plasmon resonance (SPR) sensors, in particular. In this work, an aluminum oxide (Al2O3) grating based plasmonic sensor with Si and Ag layers is proposed and simulated for the detection of hemoglobin (Hb) concentration (en route its refractive index measurement) in human blood in optical communication band (1400-1550 nm). The simulations are based on rigorous coupled wave analysis (RCWA). In general, a plasmonic sensor’s performance is closely evaluated in terms of sensitivity and figure of merit (FOM) but we have also extended the analysis by considering the SPR curves (of both reference and analyte samples) even more meticulously in terms of spectral FOM (FOM*) based on depth of reflectance curve. In order to further deepen the performance analysis, a quality factor (QF) is introduced by combining the maximum FOM* (m-FOM*) and FWHM of the analyte SPR curve. The effect of grating variables and the thicknesses of Si and Ag layers on FOM* and QF is analyzed. The simulation results are explained in relevant physical concepts such as radiation damping. The results indicate that the proposed sensor with optimized design parameters is able to provide significantly better sensitivity, detection limit, FOM, and m-FOM* compared with existing grating-based SPR sensors.
关键词： RCWA,Plasmonic nanostructure,grating,sensor,metal oxide,figure-of-merit
更新于2025-09-12 10:27:22
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Wide-band enhancement of the transverse magneto-optical Kerr effect in magnetite-based plasmonic crystals
摘要： The transverse magneto-optical Kerr effect (TMOKE) in magnetite-based magnetoplasmonic crystals is studied experimentally and theoretically. We analyze angle-resolved TMOKE spectra from two types of structures where noble metallic stripes are incorporated inside a thin magnetite film or located on top of a homogeneous film. A multiple-wide-band enhancement of the TMOKE signal in transmission is demonstrated. The complex dielectric permittivity and gyration are experimentally determined using the ellipsometry technique as well as Faraday rotation and ellipticity measurements. The obtained parameters are used in rigorous coupled-wave analysis (RCWA) calculations for studying the optical resonances. Our RCWA calculations of transmittance and TMOKE are in good agreement with the experimental data. The role of guiding and plasmonic modes in the TMOKE enhancement is revealed. We demonstrate that the TMOKE provides rich information about the studied optical resonances.
关键词： transverse magneto-optical Kerr effect,ellipticity measurements,gyration,magnetoplasmonic crystals,Faraday rotation,dielectric permittivity,optical resonances,RCWA,magnetite,TMOKE
更新于2025-09-12 10:27:22
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The importance of accurate determination of optical constants for the design of nanometallic light-trapping structures
摘要： The optical constants of many metals commonly used in solar cells, e.g. as contacts, rear side planar reflectors, or more complex nanopatterned light-trapping structures, can vary depending on deposition method, thickness and other factors, and as such are not documented consistently in the literature. In the case of nanometallic light-trapping structures specifically designed to improve absorption in a solar cell, the choice of optical constants used in simulations significantly affects the predicted enhancement, as well as the structure's optimal dimensions. The trade-off between coupling into guided modes in the photovoltaic material and the number of photons absorbed parasitically in the metal leads to small differences in the optical constants giving significantly different results for the quantum efficiency and photogenerated current. This work documents several optical constant sources for silver, aluminium, gold and titanium, and the effect this has on plasmon quality factors. The effect of choosing different optical constant sources on modelling outcomes is quantified by considering the optimization of a test structure comprising a grid of metal nanodisks on the front surface of a thinned-down GaAs cell. Finally, we define a new spectrally-integrated figure of merit for comparing the expected performance of metals in light-trapping structures based on their optical constants, which we name the spectral absorption enhancement factor (SAEF).
关键词： RCWA,Light-trapping,Metallic gratings,Surface plasmons,Ultra-thin solar cells
更新于2025-09-10 09:29:36
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asasim: Adaptive sampling for electromagnetic simulations
摘要： For simulations of electromagnetic resonance spectra, where the locations of spectral features are unknown, and for wide-band simulations in general, a substantial number of wavelengths must be simulated for acceptable resolution, increasing computation time. This problem is exacerbated for spectra containing narrow-band features, as a high spectral resolution is required to even detect them. To address this challenge, a heuristic algorithm is presented for electromagnetic simulations, which adaptively refines the local resolution of spectral features during a simulation. The method supports parallel processing and plugs in with existing simulations systems, such as rigorous coupled-wave analysis (RCWA). It can routinely reduce the computational load by two orders of magnitude.
关键词： PACS40,resolution,PACS41,rcwa,lorentzian,adaptive
更新于2025-09-09 09:28:46