Generalized Model of Beam Path Variation Induced by Axial Displacements to Spherical Mirrors in Square Ring Resonators and its Applications in Backscattering Coupling Effect
M-X. Chen, J. Yuan, X-W. Long, Z-L. Kang, Z-G. Wang and Y-Y. Li
A generalized model for beam-path variation induced by spherical mirrors’ axial displacements in square ring resonators based on ray matrix approach is established. The model can be applied to analyse beam-path variation caused by all the possible perturbation sources in various ring resonators. The generalized model is useful for the cavity design, cavity improvement, alignment of ring resonators and research on backscattering coupling effect. As a decisive error mechanism of a dual-frequency high precision laser gyro, backscattering coupling effect in square ring resonators has been chosen as an example to show the application of the model put forward in this paper. Backscattering coupling coefficient r is obtained as a function of mirror’s axial displacements. There are two cases that r is remain unchanged or varying in a wide range when the bias drift improvement loop is utilized to adjust the lasing path within the cavity in the operating laser gyro. r can be reduced to approximately zero in both cases by modifying the locations of terminal surfaces in proper ways. These methods are useful for minimizing the lock-in rate of laser gyro prior to the pump and fill process. These results are important for high precision laser gyro.
Keywords: Beam-path variation, ray matrix approach, backscattering coupling coefficient, high precision laser gyro