Selectivity analysis of femtosecond laser polarizer by three-layer grating

Abstract

The novel three-layer dielectric transmission grating under the Bragg incidence, which can be used as a polarizer, has been designed. According to the modal method, under the conditions of operating wavelength of 800 nm, duty cycle of 0.5 and period of 552 nm, the thickness of three grating layers can be roughly calculated. After that, the rigorous coupled-wave analysis method based on Maxwell’s theory is used to obtain more suitable grating parameter, which makes the grating diffraction efficiency higher. Under the Bragg incidence, the diffraction efficiencies of TE polarization in −1st order and TM polarization in 0th order can both exceed 96%. The novel three-layer grating has not only high diffraction efficiency but also the wide incident angle bandwidth. The optimized results show that the grating has good performance and good application value in the field of multi-channel laser device.