Polarization-dependent, wide spectrum and wide-angle anti-reflection grating

Abstract

Sub-wavelength 􀀁ratings (SWGs) have the property of the laser induced damage threshold (LIDT) close to that of bulk optical medium material, which becomes the focus of research to improve the anti-laser damage properties of optical element in recent years. SWGs are the effective substitutes for the laser anti-reflection (AR) of multilayer dielectric (MLD) thin films. In this paper, a polarization-dependent SWG with anti-reflection and wide-spectrum properties based on optical glass was designed using rigorous coupled wave analysis (RCWA). Figure 1 shows the schematic of the 1D grating, h is the ridge height of the grating, w is the bottom width of the grating,Λ is the period of the grating, and θ is the incident angle. The spectral characteristics were simulated using finite element analysis (FEA). The results show that the transmittance is not less than 95% from 350 nm-2500 nm in 0°~40° incident angle when the polarization component z of the electric field (TE) is parallel to the ridge direction of the grating. And it is not less than 98.5% at 0° incident angle from 350 nm to 2500 nm. When the polarization component z of the magnetic field (TM) is parallel to the ridge direction of the grating, the transmittance is not less than 95% from 300 nm to 900 nm in 0°~40° incident angle.