Interferometric Integrated Optical Gyroscope Based on Silicon Nitride Waveguide Ring

The miniaturization and integration of optical gyroscopes have urgent application demands in the field of inertial sensors. The key to achieving the miniaturization and integration of an integrated optical gyroscope (IOG) is to use waveguide-based interference ring instead of fiber loops, and their performance directly determines the detection sensitivity of the gyroscope. In this study, we successfully designed and fabricated an ultralow-aspect-ratio silicon nitride (Si3N4) waveguide interference ring with bending radius of 17.5 mm, a length of 3.003 m, a propagation loss of 13.1 dB, a coupling loss of 1.5 dB, and a footprint of 9.6 cm2. Finally, an open-loop gyroscope test system was built using the Si3N4 waveguide interference ring, and a long-term (3600 s) bias instability of 11.8°/h was successfully demonstrated. It is proved that the waveguide ring is feasible to replace the optical fiber ring. In conclusion, we believe that the successful fabrication of the Si3N4 waveguide interference ring lays a solid foundation for the miniaturization and integration of IOG and paves the way for the wider application.