Polarization beam splitter based on a double-groove slanted grating under normal incidence

In this paper, we propose a one-dimensional polarization beam splitting grating under normal incidence with excellent polarization characteristics and a high diffraction efficiency. The main structure is a double-groove slanted grating. We employed a rigorous coupled-wave analysis and simulated annealing algorithm for numerical calculations of the grating. The optimized grating structure can concentrate the energy of TE-polarized light at the -1st order and the energy of TM-polarized light at the 0th order under normal incidence. The analysis results indicate that at the incident wavelength of 1550 nm, the diffraction efficiency is 93.549% for TE polarization and 93.522% for TM polarization, with an extinction ratio greater than 14 dB. To the best of our knowledge, this is the first report of a one-dimensional polarization beam splitter grating with a transmissive double-groove slanted grating under normal incidence. This grating shows great potential for applications in polarization measurement, imaging, and grating encoders.