检索结果-内蒙古大学图书馆

High Q-factor Fano resonances based on a permittivity-asymmetric dielectric pea-shaped cylinder

APPLIED OPTICS 2023年第31期62卷 8381-8389页

作者： Pang, Jielong Fang, Wenjing Guo, Haoyu Wang, Tingting Fan, Xinye Niu, Huijuan Huang, Yongqing Bai, Chenglin Liaocheng Univ Sch Phys Sci & Informat Technol Liaocheng 252000 Peoples R China Liaocheng Univ Shandong Prov Key Lab Opt Commun Sci & Technol Liaocheng 252000 Peoples R China Liaocheng Key Lab Ind Internet Res & Applicat Liaocheng 252000 Peoples R China State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China

We numerically investigate two Fano resonances with high Q-factors based on a permittivity-asymmetric metastructure composed of two pea-shaped cylinders. By employing different materials to break the permittivity-asymmetry, the quasi-bound state of the continuum spectrum (BIC) resonance at 982.87 nm is excited, showing the Q-factor as high as 8183.7. The electromagnetic fields and vectors are analyzed by using the finite-difference time-domain (FDTD) method, and the resonance modes are identified as magnetic dipole (MD) responses and MDs by multipole decomposition in Cartesian coordinates, dis-playing that the light is confined within a pea-shaped cylinder to achieve localized field enhancement. In addition, the sensing performances of the metastructure are evaluated, and an optical refractive index sen-sor can be obtained with the sensitivity of 152 nm/RIU and maximum figure of merit (FOM) of 832.6. This proposed structure offers a new, to the best of our knowledge, way to achieve Fano resonant excita-tion on all-dielectric metastructures and can be used in nonlinear optics, biosensing, optical switches, and lasers. (c) 2023 Optica Publishing Group

关键词： Fano resonance Field enhancement finite-difference time-domain method Refractive index Resonant modes Spatial resolution

来源：评论

学校读者我要写书评

暂无评论

Surface gap solitons in the Schrödinger equation with quintic nonlinearity and a lattice potential

引用

OPTICS EXPRESS 2023年第22期31卷 35471-35483页

作者： Zeng, Liangwei Shi, Jincheng Belic, Milivoj R. Mihalache, Dumitru Chen, Junbo Li, Jiawei Zhu, Xing Guangzhou Maritime Univ Dept Basic Courses Guangzhou 510725 Peoples R China Shenzhen Univ Coll Phys & Optoelect Engn Shenzhen 518060 Peoples R China 54th Res Inst CETC Shijiazhuang 050011 Peoples R China Texas A&M Univ Qatar Doha 23874 Qatar Horia Hulubei Natl Inst Phys & Nucl Engn Bucharest 077125 Romania Jiaying Univ Sch Phys & Elect Engn Meizhou 514015 Peoples R China Minist Educ Shaanxi Key Lab Informat Photon Tech Key Lab Phys Elect & Devices Xian 710049 Peoples R China

We demonstrate the existence of surface gap solitons, a special type of asymmetric solitons, in the one-dimensional nonlinear Schrodinger equation with quintic nonlinearity and a periodic linear potential. The nonlinearity is suddenly switched in a step-like fashion in the middle of the transverse spatial region, while the periodic linear potential is chosen in the form of a simple sin (2) lattice. The asymmetric nonlinearities in this work can be realized by the Feshbach resonance in Bose-Einstein condensates or by the photorefractive effect in optics. The major peaks in the gap soliton families are asymmetric and they are located at the position of the jump in nonlinearity (at x = 0). In addition, the major peaks of the two-peak and multi-peak solitons at the position x = 0 are higher than those after that position, at x > 0. And such phenomena are more obvious when the value of chemical potential is large, or when the difference of nonlinearity values across the jump is big. Along the way, linear stability analysis of the surface gap solitons is performed and the stability domains are identified. It is found that in this model, the solitons in the first band gap are mostly stable (excepting narrow domains of instability at the edges of the gap), while those in the second band gap are mostly unstable (excepting extremely narrow domains of stability for fundamental solitons). These findings are also corroborated by direct numerical simulations. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： finite-difference time-domain method Nonlinear effects Numerical simulation Photorefractive optics Second harmonic generation Spatial solitons

来源：评论

学校读者我要写书评

暂无评论

Parallelization of a 3D FDTD code and physics studies of electromagnetic wave propagation in fusion plasmas

引用

JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 2023年第16期37卷 1366-1393页

作者： Tsironis, Christos Papadopoulos, Aristeidis Natl Tech Univ Athens Sch Elect & Comp Engn Athens Greece Natl Tech Univ Athens Sch Elect & Comp Engn Athens 15780 Greece

Numerical codes for electromagnetic wave propagation in magnetized plasmas are mainly based on frequency-domain asymptotic methods, which provide a fast solution and are thus valuable for experiment design and control applications. However, in several cases of practical interest (e.g. mode conversion), these tools run close to their limits of validity and should be compared to full-wave solutions. The code RFFW solves Maxwell's equations with the finite-difference time-domain method in 3D geometry, for scenarios involving high-frequency waves with arbitrary electric field spectrum in plasmas with axisymmetric equilibrium. In fusion-related problems, the code may conduct investigations of wave propagation and absorption relevant to auxiliary plasma heating and current drive, reflectometry and instability control. The code has been parallelized with a hybrid OpenMP-MPI scheme, which has allowed exploiting the much larger processing power and memory of current-day supercomputers. In this work, we present the main aspects of the physics implemented in the code, and also refer shortly to the parallelization scheme. Furthermore, we show results that exhibit the strong scaling performance of the code, and examine cases of electron-cyclotron heating application in medium-sized tokamaks.

关键词： Plasma waves finite-difference time-domain method electron-cyclotron heating fusion plasmas >

来源：评论

学校读者我要写书评

暂无评论

High-power narrow spectral width 975 nm semiconductor laser with high process compatibility achieved by high-order gratings

引用

OPTICS LETTERS 2023年第23期48卷 6283-6286页

作者： Liu, Zhenwu Zhong, Li Li, Wei Liu, Suping Ma, Xiaoyu Chinese Acad Sci Inst Semicond Natl Engn Res Ctr Optoelect Devices Beijing 100083 Peoples R China Univ Chinese Acad Sci Coll Mat Sci & Optoelect Beijing 100049 Peoples R China

We present broad-area semiconductor lasers with a 100th order high-order distributed Bragg reflection (HO-DBR) grating structure, fabricated with the conventional UV lithography techniques. Based on the finite-difference time domain (FDTD) algorithm, a maximum output power of 10.5 W, emitting around 975 nm with a spectral width of less than 0.5 nm FWHM has been achieved. This method provides insights for reducing the manufacturing costs of the high-power narrow spectral width DBR lasers.(c) 2023 Optica Publishing Group

关键词： Diffraction gratings Distributed feedback lasers Effective refractive index finite-difference time-domain method Scanning electron microscopy Semiconductor lasers

来源：评论

学校读者我要写书评

暂无评论

Multi-band all-silicon TM-pass polarizer based on one-dimensional photonic crystals nanohole array

引用

OPTICS LETTERS 2023年第22期48卷 6072-6075页

作者： Cheng, Guanglian Li, Qiyuan Yi, Qiyuan Yan, Zhiwei Xu, Fanglu Xiong, Xinzhe Shen, Zengfan Sima, Chaotan Li, Haicheng Shen, Li Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan 430074 Hubei Peoples R China Huazhong Univ Sci & Technol Sch Opt & Elect Informat Wuhan 430074 Hubei Peoples R China Xian Modern Control Technol Res Inst Xian 710065 Shaanxi Peoples R China

We propose an on-chip transverse magnetic (TM)-pass polarizer utilizing one-dimensional photonic crystals for multi-band operation. The TE0 modes in the 1550/2000nm wave band are suppressed by carefully selecting the pitch lengths of the nanoholes, leveraging the bandgap of the nanohole array. Conversely, the TM0 modes remain almost unaffected. The TM-pass polarizer employs a single-etched design on a standard 220 nm SOI platform and has a compact length of similar to 17.9 mu m. The simulated bandwidths (BWs) for polarization extinction ratios (PERs) > 20 dB and > 25 dB are about 210 nm and 195 nm for the 1550 nm wave band, and 265 nm and 240 nm for the 2000nm wave band. Moreover, the insertion losses (ILs) are similar to 0.5/0.3 dB at wavelengths of 1550/2000nm, respectively. For the fabricated device, the measured BWs for PER > 20 dB and > 25 dB are evaluated to be larger than 100 nm for both 1550/2000nm wave bands. The measured ILs are 1/0.8 dB at wavelengths of 1550/2000nm. This straightforward and compatible design opens possibilities for the development of practical multi -band silicon photonic integrated circuits. (c) 2023 Optica Publishing Group

关键词： Beam splitters Electron beam lithography Extinction ratios finite-difference time-domain method Hollow core fibers Thulium-doped fiber amplifiers

来源：评论

学校读者我要写书评

暂无评论

Enhancement of dual zero phonon line emissions in nanodiamonds using quasiperiodic photonic structures

引用

OPTICS LETTERS 2024年第3期49卷 510-513页

作者： Behera, Sinay Simanta Redhu, Ashish Aleem, Mohd Nair, Rajesh V. Narayan, K. S. Jawaharlal Nehru Ctr Adv Sci Res Sch Adv Mat SAMat Chem & Phys Mat Unit CPMU Bengaluru 560064 India Indian Inst Technol Ropar Dept Phys Lab Nanoscale Opt & Meta Mat LaNOM Bara Phool 14001 Punjab India

Color centers in nanodiamonds (NDs) have been largely explored by coupling to a photonic structured matrix (PSM) to amplify visible range emission features, enhancing their use in quantum technologies. Here, we study the emission enhancement of dual near-infrared zero phonon line (ZPL) emission from silicon-boron (SiB) and silicon-vacancy (SiV-) centers in NDs using a spontaneously emerged low index-contrast quasiperiodic PSM, having micron-scale air pores. An intensity enhancement factor of 6.15 for SiV- and 7.8 for SiB ZPLs is attained for the PSM sample compared to a control sample. We find Purcell enhancement of 2.77 times for the PSM sample using spatial-dependent decay rate measurements, supported by localized field intensity confinement in the sample. Such cavity-like emission enhancement and lifetime reduction are enabled by an in-plane order-disorder scattering in the PSM sample substantiated by pump-dependent emission measurements. The results put forward a facile approach to tailor the near-infrared dual ZPL emission from NDs using nanophotonic structures.

关键词： Defect center materials finite-difference time-domain method Near infrared Photonic crystal cavities Quantum technology Scanning electron microscopy

来源：评论

学校读者我要写书评

暂无评论

Global rigorous coupled wave analysis for design of multilayer metasurface absorbers

引用

OPTICS EXPRESS 2023年第24期31卷 40270-40284页

作者： Wang, Lin Fang, Debao Jin, Haibo Li, Jingbo Beijing Inst Technol Dept Mat Sci & Engn Beijing 100081 Peoples R China Harbin Engn Univ Qingdao Innovat & Dev Base Harbin 150001 Peoples R China

In this work, a novel Global NV-ETM RCWA method is proposed to accelerate the optimization of the periodic stepped radar absorbing structure. This method is based on the rigorous coupled-wave analysis (RCWA) utilizing the normal vector field (NV) and enhanced transmittance matrix (ETM) approach. The NV field dramatically improves the convergence rate for both dielectric and magnetic metasurfaces. The Global NV-ETM RCWA algorithm is developed to further accelerate the complete search calculations. Using the proposed method, the periodic stepped radar absorbing structures are efficiently optimized to realize the entire band absorption in 2-18 GHz. The optimization results demonstrate the Global NV-ETM RCWA method significantly increase the computational efficiency, with a 38-fold improvement over direct NV-ETM RCWA calculations when the truncation order N=3. This method provides a powerful tool for designing metasurface absorbers with various desired functionalities.

关键词： Composite materials finite element method finite-difference time-domain method Optical properties Reflection coefficient Rigorous coupled wave analysis

来源：评论

学校读者我要写书评

暂无评论

Improvement of light extraction efficiency in AlGaInP-based vertical miniaturized-light-emitting diodes via surface texturing

引用

OPTICS LETTERS 2024年第6期49卷 1449-1452页

作者： Cui, Siyuan Shi, Lang Jin, Leonard Zhou, Qianxi Sun, Yuechang Jin, Conglong Hu, Jiahui Wen, Kuosheng Xu, Zhou Zhou, Shengjun Wuhan Univ Ctr Photon & Semicond Sch Power & Mech Engn Wuhan 430072 Peoples R China Univ Waterloo Dept Mech & Mechatron Engn Waterloo ON N2L 3G1 Canada Jiangxi SMTC Semicond Co Ltd Nanchang 330096 Peoples R China

AlGaInP-based light-emitting diodes (LEDs) suffer from a low external quantum efficiency (EQE), which is mainly restrained by the poor light extraction efficiency. Here, we demonstrate AlGaInP-based vertical miniaturized-LEDs (mini-LEDs) with a porous n-AlGaInP surface using a wet etching process to boost light extraction. We investigated the effects of etching time on the surface morphology of the porous n-AlGaInP surface. We found that as the etching time is prolonged, the density of pores increases initially and decreases subsequently. In comparison with the vertical mini-LED with a smooth n-AlGaInP surface, the vertical mini-LEDs with the porous n-AlGaInP surface reveal improvement in light output power and EQE, meanwhile, without the deterioration of electrical performance. The highest improvement of 38.9% in EQE measured at 20 mA is observed from the vertical mini-LED with the maximum density of the pores. Utilizing a three-dimensional finite-difference time-domain method, we reveal the underlying mechanisms of improved performance, which are associated with suppressed total internal reflection and efficient light scattering effect of the pores. (c) 2024 Optica Publishing Group

关键词： finite-difference time-domain method Light extraction Photonic crystals Quantum efficiency Scanning electron microscopy Total internal reflection

来源：评论

学校读者我要写书评

暂无评论

Dark field imaging of high aspect ratio structures - a simple model

引用

OPTICS EXPRESS 2023年第23期31卷 39279-39291页

作者： Syms, Richard R. A. Kwan, Fu Yee Sydoruk, Oleksiy Imperial Coll London EEE Dept Exhibit Rd London SW7 2BX England

A simplified model for dark-field optical imaging of three-dimensional high aspect ratio micro-and nano-structures is proposed, to reduce the time taken to simulate object fields with in-plane scattering between different parts of the object. Primary scattering is found by assuming that illumination of Manhattan geometries generates a set of spherical edge waves, following the incremental theory of diffraction. Secondary scattering is found by assuming that primary scattering is re-scattered from nearby features. Diffraction coefficients are simplified, and the number of illuminating beams is limited to those generating waves that enter the objective lens. Images obtained using TE and TM polarizations are compared, and results are benchmarked against a vectorial finite element model. Applications lie in simulating optical inspection of structures containing vertically etched features including MEMS and NEMS.

关键词： Diffraction theory finite-difference time-domain method Multiple scattering Optical imaging Optical inspection Three dimensional imaging

来源：评论

学校读者我要写书评

暂无评论

Effect of optical fiber end face scratches on laser-induced damage threshold

引用

APPLIED OPTICS 2023年第31期62卷 8235-8241页

作者： Wu, Xiao Lin, Lin Zhang, Zhihang Liang, Cui Zhang, Dengwei Zhejiang Univ State Key Lab Modern Opt Instrumentat Hangzhou 310027 Peoples R China Avic Jonhon Optron Technol Co Ltd Luoyang 471000 Henan Peoples R China

The scratches on the fiber end face can enhance the local electrical field, which lowers the damage threshold. The damage mechanism of a high-energy laser is investigated. The effect of scratches on the electric field is simulated by the finite difference time domain (FDTD) solution. The results show that the depth of the scratch has a greater ability to influence the electric field than the width, and multiple scratches have a stronger modulation than a single scratch. In calculation, the damage threshold of the scratch-free end face is 0.456 J =cm(2) when the incident light electric field intensity is 50 MV =cm, compared to 0.345 J =cm(2) in the presence of the scratch on the end face. (c) 2023 Optica Publishing Group

关键词： Fiber lasers finite-difference time-domain method Laser beams Laser induced damage thresholds Multiphoton ionization Optical materials

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：