Design, Fabrication and Test of Transmissive Si3N4 Waveguide Ring Resonator

The temperature-dependent polarization induced bias drift is a major factor affecting the long-term zero-bias stability of integrated optic gyro (RIOG). The silicon nitride (Si3N4) with high-aspect-ratio core geometry allows high polarization extinction ratio and ultra-low propagation loss. We start from suppressing the polarization noise of the RIOG and design a single polarization Si3N4 waveguide ring resonator (WRR) with a radius of 17.5 mm. We established the polarization model of the WRR. It is found through simulation that when the polarization-dependent loss of the Si3N4 waveguide reaches 800 dB/m, it can maintain the single-polarization performance, thereby suppressing the polarization noise of the gyroscope. And the relationship between the coupling coefficient of the coupler and the limit sensitivity, finesse and transmittance was determined. The cross-sectional size of the Si3N4 WRR is determined to be 4 mu m x40 nm simultaneously by simulation. Finally, through its processing and testing, a single-polarizationWRR with a finesse of 127, the quality factor is 1.31x107, a transmission loss of 2.5 dB/ m, and a polarization-dependent loss of 810 dB/m is obtained. Meanwhile, we prove its single-polarization performance at different temperature. The successful design and fabrication of the WRR is expected to achieve high precision RIOG.

Automated summary

The research successfully suppressed the polarization noise of the integrated optic gyro by designing and fabricating a single-polarization Si3N4 waveguide ring resonator, improving the long-term zero-bias stability and precision of the gyroscope.