提出并设计了一种条形亚波长铝金属径向偏振光栅，用电子束直写方法制成，可以将偏振光偏振面的旋转直接转换为光斑的水平移动，通过定位光斑位移实现旋光角的测量.光栅由12 000个单元水平排列组成，每个单元宽1 μm，中心单元的格栅方向为0°，左右相邻单元的格栅分别按逆时针和顺时针方向依次旋转30″，最终实现±50°旋光角的测量范围.基于琼斯矩阵建立了光栅的理论模型，并运用严格耦合波理论分析了光栅的偏振特性与光栅脊厚、周期、占空比、入射光波长之间的关系，确定了光栅的最优结构.实验与仿真结果表明，光栅TM波的透过率大于80%、整体消光比大于26 dB.这一测量模式不受光功率波动的影响，可以构成无机械旋转的新型旋光仪，或不需要旋转图像平移转换的电力光学传感器.

This work reports the real-time observation of the interlayer lattice vibrations in bilayer and few-layer PtSe2 by means of the coherent phonon method. The layer-breathing mode and standing wave mode of the interlayer vibrations are found to coexist in such a kind of group-10 transition metal dichalcogenides (TMDCs). The interlayer breathing force constant standing for perpendicular coupling (per effective atom) is derived as 7.5 N/m, 2.5 times larger than that of graphene. The interlayer shearing force constant is comparable to the interlayer breathing force constant, which indicates that PtSe2 has nearly isotropic interlayer coupling. The low-frequency Raman spectroscopy elucidates the polarization behavior of the layer-breathing mode that is assigned to have A1g symmetry. The standing wave mode shows redshift with the increasing number of layers, which successfully determines the out-of-plane sound velocity of PtSe2 experimentally. Our results manifest that the coherent phonon method is a good tool to uncover the interlayer lattice vibrations, beyond the conventional Raman spectroscopy limit. The strong interlayer interaction in group-10 TMDCs reveals their promising potential in high-frequency (～terahertz) micro-mechanical resonators.