Csete Mária, Sipos Áron, Najafi Faraz, Hu Xiaolong, Berggren Karl K
Department of Optics and Quantum Electronics, University of Szeged, Dom ter 9, Szeged, H-6720, Hungary.
Appl Opt. 2011 Nov 1;50(31):5949-56. doi: 10.1364/AO.50.005949.
A finite-element method for calculating the illumination-dependence of absorption in three-dimensional nanostructures is presented based on the radio frequency module of the Comsol Multiphysics software package (Comsol AB). This method is capable of numerically determining the optical response and near-field distribution of subwavelength periodic structures as a function of illumination orientations specified by polar angle, φ, and azimuthal angle, γ. The method was applied to determine the illumination-angle-dependent absorptance in cavity-based superconducting-nanowire single-photon detector (SNSPD) designs. Niobium-nitride stripes based on dimensions of conventional SNSPDs and integrated with ~ quarter-wavelength hydrogen-silsesquioxane-filled nano-optical cavity and covered by a thin gold film acting as a reflector were illuminated from below by p-polarized light in this study. The numerical results were compared to results from complementary transfer-matrix-method calculations on composite layers made of analogous film-stacks. This comparison helped to uncover the optical phenomena contributing to the appearance of extrema in the optical response. This paper presents an approach to optimizing the absorptance of different sensing and detecting devices via simultaneous numerical optimization of the polar and azimuthal illumination angles.
基于Comsol Multiphysics软件包（Comsol AB）的射频模块，提出了一种用于计算三维纳米结构中吸收与光照相关性的有限元方法。该方法能够根据由极角φ和方位角γ指定的光照方向，数值确定亚波长周期结构的光学响应和近场分布。该方法被应用于确定基于腔的超导纳米线单光子探测器（SNSPD）设计中与光照角度相关的吸收率。在本研究中，基于传统SNSPD尺寸的氮化铌条纹与约四分之一波长的填充氢倍半硅氧烷的纳米光学腔集成，并被用作反射器的薄金膜覆盖，从下方用p偏振光照射。将数值结果与由类似薄膜堆叠组成的复合层的互补转移矩阵法计算结果进行了比较。这种比较有助于揭示导致光学响应中出现极值的光学现象。本文提出了一种通过同时对极角和方位角光照角度进行数值优化来优化不同传感和检测设备吸收率的方法。
