Diffractive polarizing beam splitter of two-layer grating for operation in reflection

A diffractive polarizing beam splitter (PBS) of two-layer grating is described for operation in reflection. The novel PBS grating includes two dielectric layers and a metal slab on the substrate. The reflective efficiency is widely simulated and optimized by using rigorous coupled-wave analysis. With the optimized grating parameters, efficiency of 96.46% for TE polarization of the two-layer reflective PBS grating is much more than 88.52% of the single layer PBS grating and 93.07% of the sandwiched PBS grating. The analysis shows that efficiencies more than 90% can be achieved for 394 nm spectral bandwidths within the incident wavelength range of 1480-1874 nm, which are much broader than the bandwidths of 67 nm spectral bandwidths of the reported single layer grating. The novel PBS for operation in reflection can have merits of high efficiency, broad bandwidth for incident wavelength range and high extinction ratio in the -1st order with wide angular range.