Design of a Fused-Silica Subwavelength Polarizing Beam Splitter Grating Based on the Modal Method

A polarizing beam splitter (PBS) design based on a fused-silica lamellar subwavelength transmission grating is demonstrated with the modal method, where TE-and TM-polarized waves are mainly diffracted in the -1(st) and 0(th) orders, respectively. The physical explanation of the grating diffraction is illustrated by the interference of the corresponding parts of the two propagating modes, which is very similar to a Mach-Zehnder interferometer. It is shown that diffraction efficients over 99% for a TM-polarized wave in the -1(st) order and 90% for a TE-polarized wave in the 0(th) order are obtained at the wavelength of 1.053 mu m. The polarization transmission extinction ratios are better than 33 dB and 51 dB for the order 0(th) and the -1(st) order, respectively. The splitting properties of the PBS grating designed by the modal method are in good agreement with the results simulated by the rigorous coupled wave analysis method.