A broadband thin-film polarizer with large angle tolerance

A kind of broadband thin film polarizer with large angle tolerance has been designed and fabricated. This polarizer has high extinction ratio in the incidence angle range of 53-60 and wavelength region of 1044-1088 nm. The coating design is H/L type multilayer, and employs HfO2 and SiO2 as the high and low refractive index materials. The electronic beam evaporation method is employed to evaporate the metal hafnium and SiO2 without ion beam assistance. Laser damage characteristic is investigated. The results show that the laser induced damage threshold (LIDT) of the P polarization is 20 J/cm2, and the relevant damage morphology indicates that the damage is initiated from nanosize absorbers located at the coating and substrate interface or shallow subsurface; the LIDT of the S polarization is 45 J/cm2, and the damage is initiated from nodules or contamination particles.