嵌入式光栅多层结构锥形衍射的严格耦合波理论研究

基于严格耦合波分析理论，将嵌入式光栅多层结构平面衍射的理论模型扩展至锥形衍射的情况，可以模拟具有任意波长、偏振态、方位角和入射角的平面波入射该多层结构后形成的衍射。在此基础上，研究了微机械声光传感器锥形衍射中+1 级光衍射效率的收敛性。仿真表明:TM（Transverse Magnetic）偏振光入射且光栅周期为4 m 时，当谐波数M（2n+1）分别为67、69、71 时，+1级光衍射效率分别为28.86%、28.84%、28.86%，收敛性较好。另外，优化了微机械声光传感器的位移灵敏度，当入射角为22、方位角为10、光栅周期为1 m 时，与周期为4 m 的+1 级衍射光相比，TE、TM 偏振光入射时0、+1 级衍射光的位移灵敏度均提高一倍，可以准确地监测该传感器中声压或驱动电压引起的金属膜的位移。

Rigorous coupled wave analysis of grating-embedded multilayer structure conical diffraction

Based on rigorous coupled wave analysis, the models for grating-embedded multilayer structure planar diffraction were generalized to the case of conical diffraction. The proposed method can be used to calculate the light diffracted from the grating-embedded multilayer structure with arbitrary wavelength, polarization, azimuthal angle and incident angle. For the micromachined optoacoustic sensor, the convergence performance of the diffraction efficiencies of the reflected +1st order in conical diffraction was investigated. The simulations show that using a 4m grating period and TM (Transverse Magnetic) polarization, when the numbers of harmonics M(2n+1) are 67, 69 and 71, the diffraction efficiencies of the +1st order are 28.86%, 28.84% and 28.86%, respectively. Then the displacement sensitivity of the micromachined optoacoustic sensor was optimized. When the incident angle, the azimuthal angle and the grating period are 22, 10and 1 m, respectively, compared with the +1st diffracted orders of 4 m grating period, the displacement sensitivity of the 0th and +1st orders under TE and TM polarization was nearly doubled. It can be used to accurately monitor the metal membrane displacement induced by the acoustic pressure or electrostatic actuation voltage.