Polarization beam splitter based on sub-wavelength binary grating

Because of the special diffraction characteristic of sub-wavelength grating structures, light energy with different polarization states will distribute in different diffraction orders. These gratings can obtain a high polarization extinction ratio with an appropriate set of parameters of grating structures and the incidence angle. The polarization beam splitters with different operating modes (reflective) was designed, and the finite-difference time-domain (FDTD) method was used to simulate the intensity of each diffraction order. The rigorous coupled wave analysis (RCWA) method was applied to analyze the spectral characteristics and the fabrication tolerance. The effects of the errors are clarified. In this paper, a polarization beam splitter based on grating with binary sub-wavelength structures is proposed. The ridges or grooves can be etched directly on the substrate instead of the dielectric layer. The split gratings work with an oblique incidence angle, and the waves with different polarization are distributed in different diffraction orders in the reflection or transmission area.