Broadband polarizing beam splitter based on two-layer metal grating with a high refractive index dielectric layer

A polarizing beam splitter (PBS) based on a two-layer metal grating operating in the near-infrared wavelength region is proposed. The PBS structure comprises a high refractive index dielectric layer and a subwavelength grating layer, which increases the transmittance and the extinction ratio of the grating. Using the rigorous coupled-wave analysis (RCWA) method, the parameters of the proposed polarizing beam splitter were simulated and optimized. The results show that transmission of more than 97% for the transverse-magnetic (TM) wave polarization and reflection of more than 98% for the transverse-electric (TE) wave polarization are achieved within the 1220-1690 nm wavelength range. The corresponding maximum extinction ratios for the transmittance and reflectance are 33 dB and 34 dB, respectively. When compared with a single-layer PBS grating, the proposed two-layer structure shows greater design flexibility. The proposed PBS shows potential for application to devices such as routers and switches.