Transmission polarizing beam splitter of deep-etched silicon grating

Abstract

A subwavelength transmission polarizing beam splitter (PBS) of deep-etched binary silicon grating at wavelength of 1550 nm is described, and TE-polarized and TM-polarized waves are mainly diffracted in the -1st and 0th orders, respectively. In order to achieve high extinction ratio, the grating depth and period are optimized using the rigorous coupled-wave analysis (RCWA). And the maximum extinction ratio of the rectangular PBS grating can reach 301.97 with the optimum grating period of 1291 nm and depth of 2.04 μm, the efficiencies of TE-polarized wave in the -1st order and TM-polarized wave in the 0th order are 60.07% and 73.09%, respectively. Holographic recording technology and inductively coupled plasma (ICP) etching could be used to fabricate the silicon PBS grating. Though the diffraction efficiency of the silicon PBS grating is not so high, since the silicon material is widely-used and easy to obtain; the grating structure is compact and the fabrication technology of this material is well established for mass production, the deep-etched silicon transmission PBS grating should have potential applications in optical communication systems.