High-performance reflective multilayer dielectric grating for polarization beam combining with 95.2% combining efficiency and near-diffraction-limited output

We propose a reflective multilayer dielectric grating (MLDG) for polarization beam combining. The grating enables a coaxial combination of the 0th-order TM and -1st-order TE-polarized beams, delivering high-efficiency and high-quality combined laser output while maintaining broadband performance and substantial fabrication tolerance. The self-developed grating achieves an average reflectance of 96% for the 0th-order TM wave and an average diffraction efficiency of 92% for the -1st-order TE wave across the 1030–1080 nm wavelength range. We experimentally demonstrated a combining efficiency of 95.2% at 1064 nm with near-diffraction-limited beam quality. The output M 2 factor showed only a marginal increase of approximately 0.2 compared to that of the input beams. The proposed grating offers a viable alternative to conventional polarization beam combiners, enabling high-efficiency laser output with superior beam quality.