Technical Study on Dual-Mirror Cooperative Frequency-Stabilized Induced Backscatter Angle Control for Locking Zones

The backscatter-induced lock-in effect constitutes a primary error source in laser gyroscopes, with the lock-in threshold critically dependent on the magnitude of the backscatter angle. Conventional dual-mirror synchronous frequency stabilization suffers from periodic variations in the size of adjacent longitudinal mode lock-in regions. Mode hopping, when it occurs, can severely degrade the performance of high-precision gyroscopes. To address this issue, this paper integrates beam transmission matrix theory with vector theory to simulate and analyze the variation of lock-in region thresholds under different frequency stabilization operating points using MATLAB. A novel dual-mirror cooperative frequency stabilization method is proposed. This method employs a preliminary frequency stabilization operating point obtained through mode sweeping. One stabilization mirror induces the sum of clockwise and counterclockwise backscatter angles to approach π, while the other stabilization mirror performs frequency stabilization, thereby achieving minimized control of the lock-in threshold. Experimental results demonstrate that the dual-mirror cooperative frequency stabilization method effectively eliminates periodic variations in lock-in region size between adjacent longitudinal modes. Compared to conventional dual-mirror synchronous stabilization, the lock-in threshold is reduced by approximately 38%, and laser gyroscope accuracy improves by about 53.8%. This approach provides a novel pathway for frequency stabilization control in high-precision laser gyroscopes.