Reflective three-port high-efficiency grating with two dielectric layers based on a sandwiched configuration

Abstract

In this paper, we describe a novel reflective sandwiched three-port grating with two dielectric layers. The two-layer sandwiched grating can separate incident wave into the [Formula: see text] and the 0th-order with high-efficiency beam splitting and good splitting ratios for both transverse electric (TE) and transverse magnetic (TM) polarizations. The grating parameters can be optimized by using rigorous coupled-wave analysis (RCWA) with a special duty cycle of 0.6. With the optimized results, efficiencies more than 32% in the [Formula: see text]st-orders and the 0th-order can be obtained. Furthermore, performance of the incident bandwidth and aspect ratio can be improved. Compared with conventional surface-relief grating, the grating with sandwiched structure is aimed at cleaning and protecting grating surface. The presented reflective two-layer sandwiched three-port grating would be put into practical applications for its beneficial performances.