Abstract:
In order to obtain high diffraction efficiency, high extinction ratio, wide spectrum, and large angle tolerance grating structure, a polarizing beam splitter with inverted trapezoidal double layer metal grating structure working in the near-infrared wavelength region was proposed. The PBS structure included a high refractive index dielectric layer and cut the photoresist of the grating region into an inverted trapezoidal structure, which increased the transmission efficiency and extinction ratio of the grating. Rigorous coupled-wave analysis method was used to simulate and optimize the polarization beam splitter parameters. The results show that more than 97% transmission efficiency of the transverse magnetic wave and over 95% reflection efficiency of the transverse electric wave can be achieved in the wavelength range from 1 290 to 1 840 nm. The corresponding maximum extinction ratios for the transmittance and reflectance are 33 dB and 53 dB, respectively. The proposed grating has an extinction ratios over 22 dB in the 1 550 nm wavelength and a large angle from -40 to 40, which meets the requirements for the high-performance polarizing beam splitters. Compared with the commonly used double layer metal rectangular gratings, the proposed inverted trapezoidal double layer structure exhibits higher transmittance and reflectance, which has greater design flexibility.