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Chromium-based high-temperature selective solar absorber

APPLIED OPTICS 2024年第18期63卷 4983-4992页

作者： Cao, Yuchun Feng, Yongtao Chen, Ning Liu, Haotuo Zhang, Heng Meng, Zhaoqing Wu, Xiaohu Changzhou Univ Sch Energy Changzhou 213164 Jiangsu Peoples R China Shandong First Med Univ & Shandong Acad Med Sci Med Sci & Technol Innovat Ctr Jinan Shandong Peoples R China Harbin Univ Sci & Technol Key Lab Adv Mfg Intelligent Technol Minist Educ Harbin 150080 Peoples R China Shandong Hongjitang Pharmaceut Grp Co Ltd Jinan 250103 Peoples R China Shandong Inst Adv Technol Thermal Sci Res Ctr Jinan 250100 Peoples R China

Selective solar absorbers play a pivotal role in harnessing renewable energy sources and offer considerable potential for efficient photothermal conversion. However, most highly efficient solar selective absorbers require complex structural designs or combinations of multiple materials to implement. Here, we design a spectrum selective solar absorber using only chromium, featuring a cross-shaped square cavity structure. The absorber exhibits a total solar absorption of 96.2% while maintaining a total emissivity of 12%. The distributions of electric field indicate that the outstanding spectrum absorption is caused by the synergistic interplay between surface plasmon resonance, cavity resonance, and guided mode resonance. Our study delves into how different geometric parameters influence the spectrum absorption of the absorber. Additionally, we investigate the performance of the selective solar absorber in terms of absorption at various angles of incidence. Remarkably, even at a substantial angle of 60 degrees, it sustains a high absorption of approximately 80%. At 100 degrees C, the absorber achieves an 86% photothermal conversion efficiency. Furthermore, as the concentration factor increases, the impact of high temperature on the absorber's photothermal conversion efficiency diminishes. When the concentration factor is 200, the absorber achieves a steady-state temperature exceeding 753 degrees C. This work holds importance in photothermal conversion and thermophotovoltaics. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： finite-difference time-domain method Solar energy Subwavelength structures Surface plasmon resonance Thin films Waveguide modes

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Near-to-far-field transformation scheme utilizing a modified sinc interpolation method for PSTD simulations

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OPTICS EXPRESS 2024年第26期32卷 47225-47235页

作者： Liu, Jake w. Tseng, Snow h. Natl Taiwan Univ Grad Inst Photon & Optoelect Taipei 10617 Taiwan

We present a near-to-far-field (NTFF) transformation scheme tailored for pseudospectral time-domain (PSTD) simulations. Surface currents on the NTFF boundary are computed using a modified sinc interpolation method, eliminating the need for local averaging required infinite-difference time-domain (FDTD) simulations. Numerical results for dielectric sphere scattering, compared with Mie solutions, demonstrate that the proposed PSTD scheme achieves root-mean-square errors an order of magnitude lower than FDTD for the far-field patterns. The sinc interpolation method exhibits exceptional accuracy, even when applied to coarse grids. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Electromagnetic scattering finite-difference time-domain method Fourier transforms Mie scattering Refractive index Spectral properties

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Tunable triple plasmon-induced transparency in E-type graphene metamaterials

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OPTICS EXPRESS 2024年第14期32卷 25435-25450页

作者： Lei, Pengliang Nie, Guozheng Li, Huilin Liu, Nanliu Xnglin, Li Peng, Liang Tang, Xiaofang Gao, Enduo Hunan Univ Sci & Technol Sch Phys & Elect Sci Xiangtan 411201 Peoples R China Hunan Prov Key Lab Intelligent Sensors & New Senso Xiangtan 411201 Hunan Peoples R China Qiannan Normal Univ Nationalities Sch Phys & Elect Qiannan 558000 Peoples R China Changsha Univ Sci & Technol Sch Phys & Elect Changsha 410083 Peoples R China

Enhancing light-matter interaction is crucial for boosting the performance of nanophotonic devices, which can be achieved via plasmon-induced transparency (PIT). This study introduces what we believe to be a novel E-type metamaterial structure crafted from a single graphene layer. The structure, comprising a longitudinal graphene ribbon and three horizontal graphene strips, leverages destructive interference at terahertz frequencies to manifest triple plasmon-induced transparency (triple-PIT). Through a comparison of simulations using the finite difference time domain (FDTD) method and theoretical coupled-mode calculations, we elucidate the physical mechanism behind triple-PIT. Our analysis shows that the PIT effect arises from the interplay between two single-PITs phenomena, further explored through field distribution studies. Additionally, we investigate the impact of varying Fermi levels and carrier mobility on the transmission spectrum, achieving amplitude modulation in photoelectric switches of 85.5%, 99.2%, and 93.8% at a carrier mobility of 2 m2/(Vs). Moreover, we explore the relationship between Fermi levels and carrier mobility concerning the slow light effect, discovering a potential group index of up to 1021 for the structure. These insights underscore the significant potential of this graphene-based metamaterial structure in enhancing optical switches, modulators, and slow light devices.

关键词： Coupled mode theory Destructive interference finite-difference time-domain method Light matter interactions Surface plasmon polaritons Third harmonic generation

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Rotationally symmetric transverse magnetic vector wave propagation for nonlinear optics

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OPTICS EXPRESS 2024年第10期32卷 17853-17868页

作者： Grimms, Caleb J. Nevels, Robert D. Texas A&M Univ Dept Elect & Comp Engn 188 Bizzel St College Stn TX 77801 USA

In this paper the theory and simulation results are presented for 3D cylindrical rotationally symmetric spatial soliton propagation in a nonlinear medium using a modified finite -difference time -domain general vector auxiliary differential equation method for transverse magnetic polarization. The theory of 3D rotationally symmetric spatial solitons is discussed, and compared with two (1 + 1)D, termed "2D" for this paper, hyperbolic secant spatial solitons, with a phase difference of pi (antiphase). The simulated behavior of the 3D rotationally symmetric soliton was compared with the interaction of the two antiphase 2D solitons for different source hyperbolic secant separation distances. Lastly, we offer some possible explanations for the simulated soliton behavior.

关键词： Computer simulation Effective refractive index finite-difference time-domain method Nonlinear optics Spatial solitons Wave propagation

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Simple strategy for the simulation of axially symmetric large-area metasurfaces

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2024年第5期41卷 1261-1269页

作者： Martins, Augusto da Mota, Achiles F. Stanford, Chris Contreras, Taylor Martin-Albo, Justo Kish, Alexander Escobar, Carlos O. Para, Adam Guenette, Roxanne Univ Manchester Dept Phys Manchester M13 9PL England Harvard Univ Dept Phys Cambridge MA 02138 USA Univ Brasilia Dept Elect & Comp Engn BR-70910900 Brasilia DF Brazil CSIC Inst Fis Corpuscular IFIC Calle Catedrat Jose Beltran 2 E-46980 Paterna Spain Univ Valencia Calle Catedrat Jose Beltran2 E-46980 Paterna Spain Fermilab Natl Accelerator Lab Batavia IL 60510 USA

Metalenses are composed of nanostructures for focusing light and have been widely explored in many exciting applications. However, their expanding dimensions pose simulation challenges. We propose a method to simulate metalenses in a timely manner using vectorial wave and ray tracing models. We sample the metalens's radial phase gradient and locally approximate the phase profile by a linear phase response. Each sampling point is modeled as a binary blazed grating, employing the chosen nanostructure, to build a transfer function set. The metalens transmission or reflection is then obtained by applying the corresponding transfer function to the incoming field on the regions surrounding each sampling point. Fourier optics is used to calculate the scattered fields under arbitrary illumination for the vectorial wave method, and a Monte Carlo algorithm is used in the ray tracing formalism. We validated our method against finite -difference time domain simulations at 632 nm, and we were able to simulate metalenses larger than 3000 wavelengths in diameter on a personal computer.

关键词： Diffraction efficiency Diffractive optical elements Endoscopic imaging finite-difference time-domain method Fourier optics and optical processing Ray tracing

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Simulation of the channel current and radiated electric field for artificially triggered lightning

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2025年第4期42卷 773-779页

作者： Shen, Xiaozhi Xu, Yao Liu, Mingyuan Zhang, Huaming Wang, Huaying Hebei Univ Engn Sch Sci & Engn Math & Phys Handan 056038 Peoples R China Tianjin Normal Univ Sch Phys & Mat Sci Tianjin 300387 Peoples R China Chinese Acad Sci Inst Atmospher Phys Beijing 100029 Peoples R China Meteorol Disaster Prevent Technol Ctr Shanxi Prov Taiyuan 030002 Peoples R China

Spectrographic analysis was performed to determine the plasma composition of artificially triggered lightning in Guangzhou, China, by about N I, N II, O I, O II, and Fe II. Different engineering models were adopted to simulate the channel current (i) of triggered lightning, the changing rate of current over time ( di of current over time and height [ di d(tH)]. It is indicated that the modified transmission line model with linear current decay with height (MTLL) can simulate a moderate channel current. The experimental current is found to be stronger than the simulation at the bottom of the channel, and it is predicted that the addition of iron ions affects the channel current. Furthermore, based on a finite-difference time-domain simulation, the radiated electric field of the return stroke of triggered lightning is found more varied than that of natural lightning. This forms a phenomenon of an overshoot amplitude electric field in triggered lightning. It is predicted that the addition of iron ions in the channel current affects the distribution of the radiated electric field. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： Attenuation finite-difference time-domain method Measuring instruments Metals Numerical simulation Spectrometers

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Plasmonic refractive index sensor of a hexagonal close-packed gold nanodisk array coupled with a gold thin film

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2025年第6期42卷 1251-1257页

作者： Zhu, Huirong Wang, Xiangxian Chen, Yizhen Rao, Xijun Qi, Yunping Yang, Hua Lanzhou Univ Technol Sch Sci Lanzhou 730050 Peoples R China Northwest Normal Univ Coll Phys & Elect Engn Lanzhou 730070 Peoples R China

The study proposes an innovative surface plasmon refractive index sensor based on a hexagonal close-packed gold nanodisk array coupled with a gold thin film. The composite structure comprises a SiO2 substrate, an Au thin film, a SiO2 spacer layer, and a hexagonal close-packed Au nanodisk array. The study used the finite-difference time-domain method to investigate the surface plasmons excitation characteristics, optical field distribution, and refractive index sensing properties of the composite structure. The composite structure excited three surface plasmon resonance (SPR) modes in a liquid environment. The study investigated the influence of structural parameters on the three SPR modes. The sensing performance of the composite structure was studied in gas environments (n= 1.00-1.10) and liquid environments (n= 1.33-1.40). The maximum sensitivity (S) and the maximum figure of merit (FOM) could reach 1297 nm/RIU and 260 RIU-1 in gas environments, and 1291 nm/RIU and 208 RIU-1 in liquid environments. The sensor has the advantages of high sensitivity, a high FOM, a simple structure, and easy processing. This study obtains excellent sensing performance by changing the arrangement of Au nanoparticles, providing a reference for designing surface plasmon refractive index sensors based on the coupling structure of a metal nanoarray and a metal thin film. The sensor can be used in a broad range of biochemical detection applications, such as detection of hemoglobin concentration and temperature sensing. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： Diffraction limit finite-difference time-domain method Optical fields Refractive index Surface plasmons Thin films

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Uncovering the underlying electromagnetic mechanism of lead-free all-perovskite tandem solar cells with ZnO moth-eye antireflection layers

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DYES AND PIGMENTS 2025年 235卷

作者： Seo, Kyeong-Ho Biswas, Swarup Lee, Yongju Lang, Philippe Gil, Dohyeon Choi, Minsu Bae, Jin-Hyuk Kim, Hyeok Kyungpook Natl Univ Sch Elect & Elect Engn 80 Daehakro Daegu 702701 South Korea Univ Seoul Ctr Smart Sensor Syst Seoul CS4 Sch Elect & Comp Engn 163 Seoulsiripdaero Seoul 02504 South Korea

As the push to enhance power conversion efficiency (PCE) in solar cells intensifies, tandem configurations that integrate photovoltaic devices with complementary bandgaps have become essential. Perovskite materials are particularly advantageous in these tandem solar cells due to their adjustable bandgaps (ranging from 1.2 to 2.2 eV), superior light absorption, remarkable structural stability, and efficient charge-carrier mobility. Lead-free perovskites offer the benefits of traditional perovskites while also being nontoxic and stable;thus, they are ideal candidates for tandem solar cells. However, the optical loss associated with light reflection from the upper surface of the cell degrades device performance, thus reducing the PCE of solar cells;therefore, continuous research efforts are needed to address this drawback. In this study, we coated a lead-free all-perovskite tandem solar cell with a parabolic zinc oxide (ZnO) moth-eye antireflection (AR) layer and assessed its efficiency in suppressing reflection using the two-dimensional finite-difference time-domain method. We analyzed the maximum short-circuit current density (Jsc,max) of the lead-free all-perovskite tandem solar cell by varying the height (H) of the ZnO moth-eye AR layer. Notably, for H = 300 nm, Jsc,max was about 30.5 mA/cm2, which indicated that 300 nm was the optimal height for performance improvement. Moreover, we generated a profile for the light-trapping phenomenon that occurs within an actual cell by simulating the electromagnetic mechanism governing the generation rate and proportion of absorbed photons. This profile enabled us to characterize the light-trapping phenomenon within the tandem solar cell induced by the ZnO moth-eye AR layer.

关键词： Power conversion efficiency Lead-free perovskites Zinc oxide moth-eye antireflection layer finite-difference time-domain method Electromagnetic mechanism

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Estimation of Apparent Ionospheric Reflection Height from LEMP Waveforms for the Case of Tilted Lightning Channel

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IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY 2025年第2期67卷 521-529页

作者： Ichikawa, Yuto Baba, Yoshihiro Tsuboi, Toshihiro Rakov, Vladimir A. Doshisha Univ Kyoto 6100394 Japan TEPCO Res Inst Kanagawa 2300002 Japan Univ Florida Dept Elect & Comp Engn Gainesville FL 32611 USA

The interaction of lightning electromagnetic pulse with the ionosphere has been often analyzed using the finite-difference time-domain method in the 2-D cylindrical coordinate system or in the 2-D spherical coordinate system. In this article, time-update equations for electric and magnetic fields in the 3-D spherical coordinate system are presented, and vertical electric fields at far distances over the curved surface of the Earth from the base of a vertical or tilted lightning return-stroke channel are computed. The lightning channel is represented by the modified transmission-line model with linear current decay with the distance along the channel. A realistic channel-base current waveform with a risetime of 3 mu s represented by the Heidler function is used. The ionosphere is simulated by a nonuniform medium whose conductivity increases exponentially with altitude. Apparent ionospheric reflection heights are estimated based on the arrival time difference between the ground wave and the first skywave. When the arrival times of ground wave and skywave are defined as the arrival times of their field peaks, the estimated ionospheric reflection height depends on channel tilt angle and increases with increasing field observation distance. In contrast, when the arrival times of ground wave and skywave are defined as the arrival times of 80% of their field derivative peaks, the estimated ionospheric reflection height is not much influenced by either distance or channel tilt angle.

关键词： Lightning Ionosphere Three-dimensional displays Mathematical models time-domain analysis Computational modeling Channel estimation finite difference methods Electromagnetic compatibility Surface waves 3-D spherical coordinate system finite-difference time-domain method ionosphere lightning lightning electromagnetic field lightning return-stroke channel

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Photonic jet generated by a silicon nitride spherical particle with shaped beam illumination

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APPLIED OPTICS 2025年第4期64卷 1055-1067页

作者： Liu, Anran Han, Lu Northwest Univ Sch Phys Xian 710127 Peoples R China

Photonic jets (PJs) are generated by the interaction between beams and dielectric particles, resulting in narrow, high-intensity beams produced behind the medium. Silicon nitride exhibits excellent optical properties;we aim to explore the potential of silicon nitride in PJ applications. In this paper, the beam is expanded by spherical vector wave functions with the framework of the generalized Lorenz-Mie theory (GLMT). Numerical simulations are performed to investigate the PJs generated by silicon nitride spherical particles illuminated by the plane wave, Gaussian beam, and zero-order Bessel beam under water;the effects of various parameters on the characteristics of PJs are further examined. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： finite-difference time-domain method Gaussian beams Numerical simulation Optical properties Raman scattering Silicon nitride

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