Interferometric Fiber Optic Gyro Based on High-Performance Passive Si₃N₄ Chip

A high-performance miniaturized fiber optic gyro (FOG) with optimized size, weight, and power is crucial for advanced inertial measuring units (IMUs). To partially replace bulky discrete passive optical components, an optical passive chip fabricated on an ultralow-loss silicon nitride photonic platform was developed. This chip boasts impressive performance characteristics, including full-temperature insertion loss (this refer to the insertion loss measured across various temperature ranges) of less than 11.2 dB, a polarization extinction ratio (PER) exceeding 28 dB, and an edge coupling loss of less than 1 dB/facet. Further tests of the IFOG based on the passive chip have demonstrated a bias instability of up to 0.009°/h, which is the best result of the same type IFOGs reported to date, to the best of our knowledge. The viability of passive chips in high accuracy, low cost, and compact IFOGs has been fully demonstrated.