Direct Coupling Technology of Hollow-Core Microstructure Fiber Optic Gyroscope

Hollow-core microstructure fiber (HMF) can achieve high-quality air light guidance, air as the transmission medium, the transmission of optical signals will no longer be sensitive to temperature, magnetic field and other environmental factors, which can fundamentally improve the environmental adaptability of fiber optic gyroscope (FOG). However, the assembly between hollow microstructure fiber and gyroscope traditional optical path is an urgent engineering problem. In this paper, an optical path assembly method is proposed for realizing the direct coupling of bare Y waveguide chip and HMF coil by introducing a combination of micro lenses and reflective mirror between the bare Y waveguide chip and the cleaved end of HMF pigtail. The direct coupling experiment results show the single-ended coupling loss is less than 0.5 dB, and the single-ended polarization crosstalk is better than -30 dB. A HMF gyroscope is constructed by using the fabricated direct coupling assembly of Y waveguide chip and HMF coil, and the bias instability of the HMF gyroscope is better than 0.005°/ h.