全内反射式衍射光栅近场光学特性

Near-field optical property of diffraction grating based on total internal reflection

利用傅里叶模式理论分析了具有高衍射效率的全内反射式衍射光栅在TE和TM偏振态下的近场光分布特点,讨论了光栅结构参数以及入射角度对光栅内电场增强的影响。结果表明:全内反射光栅内部电场分布对偏振态较敏感,光栅槽深和占宽比对电场增强影响较小,光栅内的峰值电场随光栅周期增大而增大,并且峰值电场随着入射角度的增大而减小。在应用于高功率激光时,降低光栅内部的电场增强可以有效降低损伤风险。

Using Fourier model method, the near-field distribution of a total interual reflection（TIR） grating with high efficiency was analyzed under the irradiation of different polarized lights. The dependence of electric field enhancement in the TIR grating on constructive parameters and incident angle was also discussed. It is shown that electric field in the grating is sensitive to the polarization state, and peak electric field can be reduced greatly with short period and also decreases linearly with the increasing of incident angle. For the application of TIR grating to the high-energy laser system, reduction of the internal field enhance- ment can avoid the danger of damage effectively.