Design of Silicon Nitride Based TE-Pass Polarizer at 850 nm for Integrated Fiber Optic Gyroscope

Abstract

In recent years, the rapid development of integrated optics provides a novel approach to realize miniaturized and lightweight fiber optic gyroscope (FOG). This paper proposes a TE-pass polarizer based on the silicon nitride on insulator (SNOI) platform operating at 850 nm, whose insertion loss is lower than 1.02 dB with the polarization extinction ratio (PER) larger than 47 dB. The proposed polarizer could directly edge-couple to the thin film lithium niobate (TFLN) modulator with a negligible loss (<0.19 dB) to form a combined hybrid modulator, which integrates the function of modulating, splitting, and polarizing. Compared with the traditional bulk lithium niobate modulator, the utilization of the hybrid modulator in FOGs could increase the optical power entering the fiber coil by 68% at 850 nm, which greatly facilitates the improvement of FOG precision. Furthermore, the undesired residual intensity modulation effect in the bulk lithium niobate modulator is also theoretically avoided by employing the hybrid modulator.