Design of fused-silica transmission gratings for orthogonal polarizing beam combiners

Deep-etched rectangular fused-silica transmission gratings used as orthogonal polarizing beam combiners at the wavelength of 532 nm are designed based on the modal method. The fabrication tolerances and the properties of the orthogonal polarizing beam combiners are analyzed by rigorous coupled-wave analysis. It is shown that these gratings have large fabrication tolerances and good properties when the diffraction efficiencies are greater than 90%. The optimal grating is highly efficient (>95%) over broad incidence condition and also has large fabrication tolerances.