Embedded dual-layered dielectric slit arrays under second Bragg incidence for 1 x 3 splitting field propagation

Embedded double-layer transmission grating beam splitter under the second Bragg incidence is presented in this paper. With a given duty cycle of 0.5 and a period of 940 nm, we use rigorous coupled-wave analysis method to investigate this beam splitter. The grating parameters are optimized for high-efficiency output. Each efficiency of the three orders under polarizations of TE and TM is close to 33.3 % respectively. Compared with the single-layer fused-silica grating, the three-port double-layer grating is flexible with complex structure and stable in performance. The field distribution modal method are given, which can well explain the propagation process and coupling mechanism.