任意面形介质光栅的衍射特性分析

采用严格耦合波理论(RCWA)和多层近似法,详细的推导了任意面形介质光栅的衍射问题,得出了其矩阵求解方程,并采用增强透射矩阵法来避免直接求解带来的数值不稳定,提高了计算效率.使用该方法对梯形光栅进行了数值计算,结果表明采用严格耦合波理论和多层近似法,可以方便、有效地求解任意面形介质光栅的衍射效率问题,计算中光栅在不同参数下衍射效率的总和严格等于1,且未有数值不稳定性问题.     

Tunable Guided‐Mode Resonance Grating Filter

The optical characteristics of shallow 2D nanostructured polycarbonate samples are presented. Tunable guided‐mode resonance filters are experimentally demonstrated for the visible spectral range when functional coatings are applied to 2D nanostructures by means of atomic layer deposition. The wavelength position of the reflection peaks can be easily tuned in a broad range (>150 nm) through rotation of the optical element around the axis normal to the substrate without changing the rest of the optical setup. Rigorous coupled wave approach simulation of model systems is performed to obtain insight into the complexity of the optical properties of these systems. The photonic nanostructures presented here are promising optics for application in ultra‐compact, portable, miniaturized optical systems.     

Cylinder and metal grating polarization beam splitter

We propose a novel and compact metal grating polarization beam splitter (PBS) based on its different reflected and transmitted orders. The metal grating exhibits a broadband high reflectivity and polarization dependence. The rigorous coupled wave analysis is used to calculate the reflectivity and the transmitting spectra and optimize the structure parameters to realize the broadband PBS. The finite-element method is used to calculate the field distribution. The characteristics of the broadband high reflectivity, transmitting and the polarization dependence are investigated including wavelength, period, refractive index and the radius of circle grating. When grating period d = 400 nm, incident wavelength λ = 441 nm, incident angle θ = 60° and radius of circle d/5, then the zeroth reflection order R₀ = 0.35 and the transmission zeroth order T₀ = 0.08 for TE polarization, however, T₀ = 0.34 and R₀ = 0.01 for TM mode. The simple fabrication method involves only single etch step and good compatibility with complementary metal oxide semiconductor technology. PBS designed here is particularly suited for optical communication and optical information processing.     

基于严格耦合波理论的亚波长金属光栅偏振器设计①

亚波长周期结构光栅具有传统光栅所不具有的特殊性质.针对仿生微纳导航系统敏感波段0.52-0.59μm的要求,采用严格耦合波理论分析了不同光栅材料、光栅面型及光栅结构参数对TM偏振透射率及透射消光比的影响,设计了对应的金属偏振光栅.所设计的光栅与传统金属光栅不同之处在于基底和光栅之间增加了氟化镁介质,在垂直入射条件下,TM偏振透射率及消光比都增大.在0.38μm～0.40μm及0.50μm～0.76μm全光波段内,TM偏振透射率都大于50%,消光比都大于170,达到了宽带宽、TM偏振透射率及透射消光比都较高的要求.     

亚波长周期结构抗反射介质光栅的衍射特性

用严格耦合波理论(RCWA)计算了当折射率取一系列离散值时的二维亚波长周期结构介质光栅出现一级衍射透射波的周期值,进而利用最小二乘法拟合出临界周期点随折射率的变化规律;利用一维单台阶和多台阶光栅在TE、TM偏振状态以及二维单台阶圆柱状光栅和二维金字塔结构多台阶光栅进行验证,发现它们同样满足临界周期点的变化规律。结果证明,对于任意面形的亚波长周期结构介质光栅的一级衍射效率都有这一规律。     

RCWA方法设计阶梯形光学生物分子检测探针

设计了一种阶梯形光学生物分子检测探针,并利用严格耦合波分析（RCWA）法计算了此探针的反射光谱的反射效率。模拟结果表明,此探针的反射谱中特定峰值处,探针周围的待测物折射率与探针的入射角间呈线性变化,且探针反射效率与待测物折射率和入射角均符合左半高斯型曲线分布。所以,既可应用入射角来反映待测物折射率的变化,也可利用反射效率的变化反映待测物折射率的变化。基于此研究的方法和结果可广泛应用于生物传感器和生物分析等研究领域。     

光通信C波段硅基导模共振窄带滤波器的模拟

结合严格耦合波理论和遗传算法对C波段硅基导模共振滤波器进行了模拟分析.从模拟结果出发详细讨论了光栅周期、填充因子、光栅深度和入射角度对滤波器反射特性的影响.导模共振对光栅周期、填充因子、光栅深度和入射角度都有很高的敏感性,利用这一特点可以设计性能优异的硅基滤波器件.导模共振滤波器的共振波长峰值反射率达到了98.9%,峰值半高宽小于密集渡分复用(DWDM)O.8 nm的要求.

Abstract：

Simulated are silicon-based guided-mode resonant grating filters with narrow bandwidth for C-band optical communication.The effects of the characteristics of grating period,fill factor,the grating depth,the thickness of SiO_2 layer and incident angle on the reflection mechanisms of the filters are analyzed in detail based on the simulation results.Guided-mode resonant effect is very sensitive to such characteristics,which can be used to optimize silicon-based filters.The reflectance of the resonant wavelength of this filter reaches 98.9%,and the FWHM (full width at half maximum) is less than 0.8 nm limited by the DWDM (dense wavelength division multiplication) system.     

Improved rigorous coupled-wave analysis for polar magnetic gratings

The rigorous coupled-wave analysis method with Airy-like Internal-Reflection Series for the polar gyrotropic grating is improved with the Fourier factorization rule. In the process of derivation, Maxwell's equation is reformulated in order to avoid type 3 product and, either Laurent's rule or the inverse rule is used for the product of two Fourier series with discontinuities. The number of Fourier coefficients or the size of the coefficient matrix required for the proper convergence is reduced by more than 50% compared to our previous works for the calculation of the diffracted Kerr rotation from the polar magnetic gratings.     

面向高效单结GaInP太阳电池的介质复合纳米结构的仿真研究

以实现宽谱减反介质复合纳米结构表面的高 效单结GaInP太阳电池为目标,利用严格耦合波分析理论, 仿真研究了该电池表面的介质复合纳米结构对太阳电池宽谱减反、归一化吸收、最大化理想 效率的影响。该介质复 合纳米结构从上往下依次为SiO₂纳米锥、SiO₂介质层和SiNx介质层,通过对SiO₂纳米锥占空比、深宽比以及对SiO₂和SiNx介质层厚度等参数的系列仿真最终优化出适用于单结Ga InP电池的表面结构。结果表明:当SiO₂纳米锥底部 直径D=550nm、高度H=650 nm、SiN x介质层厚度为60 nm时电池具有最高的 最大化理想转换效率为28.58%。上述结果为后期实验以及该类电池 实现规模化生产奠定了基础。     

基于RCWA方法设计的甲醛传感器的研究

针对日常生活中甲醛损害人们健康的问题,该文采用严格耦合波分析（RCWA）法设计了一种能快速、高精度实时检测甲醛溶液浓度的光学传感器。该传感器以多孔二氧化锆(ZrO2)介孔材料作为甲醛的承载单元,TiO2和SiO2光栅分别作为波导层和光耦合层构成的层状复合结构。利用RCWA法计算了该传感器的透射光谱,建立了透射共振峰波长与待测甲醛溶液浓度间的关系模型,并分析了其传感特性。结果表明,该传感器具有较高的灵敏度和良好的重复稳定性,品质因数Q=1 261,灵敏度可达0.101 nm/%,并可实现对待测甲醛溶液浓度的实时动态监测。