Polarization Characteristics of the Near-Field Distribution of One-Dimensional Subwavelength Gratings

To improve the anti-laser damage performance of one-dimensional (1D) subwavelength gratings (SWGs), this paper proposes to reasonably reduce the peak electric field at the grating ridges to further reduce the laser damage caused by the electric field contribution. Based on Maxwell’s equations, the equations for solving the field intensity of the near-field distribution of the dielectric materials are derived. The numerical simulation theoretical model is described. A 1064 nm laser in the –y direction irradiates the geometric surfaces under two perpendicular polarization directions: perpendicular to the grating ridges (transverse magnetic wave (TM) or x-polarization) and parallel to the grating ridges (transverse electric wave (TE) or z-polarization). We discuss the effects of the profile shape, structural parameters and refractive index of the material on the near-field distribution at the 1D SWG ridges by using a finite element method (FEM). The near-field distribution is sensitive to the x- and z-polarization of incident light. The near-field distribution of the 1D SWGs for TM waves is modulated by the surface, whereas that for TE waves is similar to the distribution of the bare substrate. The results show that the near-field distribution of 1D SWGs greatly depends on the laser polarization direction.