Gratings in dispersion-compensated polarization Sagnac interferometer

Abstract

A dispersion-compensated polarization Sagnac interferometer (DCPSI) can obtain interference fringes, and then be applied to many fields. Using two identical blazed gratings in DCPSI, and the grating period of blazed gratings should be considerably larger than the wavelength, which means that the grating period has its limitations and the different grating period will affect the quality of interference fringes. Aside from the grating period, the influence of other parameters on the interference fringe is also considered, such as substrate thickness and blaze angle. Kudenov theory is recalculated from the grating equation without any approximation to reveal the limitation of the grating period. Substrate thickness and the blaze angle of the grating are then investigated. The influence of the grating parameters on interference fringes is finally confirmed through simulation and experiment. The results of this study are important for guiding researchers in choosing gratings to obtain clear interference fringes.