Optimization method of phase-shift structure for polarization beam-splitter

A polarization beam splitter based on subwavelength grating is theoretically analyzed. The design methods of phase-shift structure are given to split the TE and TM polarized waves, the optimum parameters of relief phase-shift structure with high extinction ratio at the wavelength of $10.6\mu\mathrm{m}$ and 1550nm are reported respectively.