Analysis and Optimization of the Sandwiched Metal-Dielectric Polarizing Beam Splitter Grating

A reflective sandwiched polarizing beam splitter (PBS) grating with a connecting layer in Littrow mounting is described and designed in this paper. By using two-beam-interference theory for a modal method, a duty cycle and a period of grating can be calculated, where the first order is well suppressed for transverse magnetic (TM) polarization. In addition, the grating groove depth can be roughly evaluated, in which the zeroth order is well restrained for transverse electric (TE) polarization. By using numerical optimization for rigorous coupled-wave analysis, some of exact parameters of grating are obtained. On the basis of the precise numerical results, the diffraction efficiencies in the first order and in the zeroth order for TE polarization and TM polarization are enhanced, respectively. Most importantly, compared to the reported surface-relief reflective PBS gratings, the grating extinction ratio and incident spectrum band width can be improved greatly. Therefore, this highly efficient PBS wideband grating with high extinction ratio would become excellent optical diffraction device.