提出了一种基于块状亚波长光栅的偏振不敏感宽光谱高反镜的设计方法。亚波长光栅的反射性能由光栅的结构参数即周期和占空比决定，优化周期和占空比值将使亚波长光栅在更宽的光谱范围内具有更高的反射率。采用严格耦合波分析法计算不同周期下光栅的反射率，再构造一个集合包含所有反射率超过99%的光栅周期值，运用迭代优化算法，减小集合的数据规模，从而快速确定最优的光栅周期值和它对应的占空比值。仿真结果显示，使用标准的绝缘体上硅（SOI）晶片制作的二维块状亚波长光栅反射镜将在182 nm的光谱范围内保持超过99%的反射率，同时光栅的反射特性与垂直入射光的偏振态无关，但是当入射角大于7°时在1439～1621 nm的波长范围内光栅的反射率将无法始终保持在99%以上。因此，可以将二维块状亚波长光栅应用在垂直腔面激光器上，用于激光多普勒测速或者构建光缓存的二维网络。最后，通过数值仿真证实，在二维块状亚波长光栅反射镜的制作过程中，允许周期值和占空比值存在一定的误差。

An approach of designing polarization-insensitive, broadband spectrum, high-reflectivity mirror based on blocky structure with subwavelength grating is proposed. The reflectance properties of subwavelength grating are determined by structure parameters of grating such as period and duty cycle. Optimizing the period and duty cycle can get a higher reflectivity at broader spectrum. The reflectivities of grating with different periods are calculated by rigorous coupled wave analysis. A set is formed with grating periods of reflectivities over 99%. The size of data set is reduced using an iterative optimization algorithm, which can quickly determine the optimal grating period and the corresponding duty cycle. The simulation results show that two-dimension blocky structure with subwavelength grating mirror fabricated with standard silicon-on-insulator (SOI) wafer can keep the reflectivity over 99% at a spectrum range of 182 nm. Meanwhile the reflectance properties of grating is independent of polarization of vertical incident light. But it can′t keep the reflectivity over 99% at a wavelength range from 1439 nm to 1621 nm anymore as the incident angle up to 7°. So the can be applied on vertical cavity surface emitting lasers (VCSEL) to achieve velocity measurement of laser Doppler or two-dimension network structure of optical buffer. Furthermore, numerical simulations show that the working process of two-dimension blocky structure with subwavelength grating mirror has some tolerance of period and duty cycle.