Research On Bias Difference Of The Intermodes In Ring Laser Gyro

With the development of current physics and inertial technology, Ring Laser Gyro(RLG) has been a developing direction of the inertial gyro for its unique characteristics. A phenomenon was found while developing the RLG: the bias of the RLG is related to the length of the resonant cavity with the cycle of two wavelengths. In the applications, the cavity length used in RLG is random selected, and accordingly, the bias is also random, which reduces the accuracy of the RLG. So it's necessary to research the reason of formation to improve the accuracy of the RLG.Based on the back scattering, some studies are made to research the lock-in and bias of RLG. By using a complex amplitude reflectance to represent the effect of coupled back scattering of all the reflectors in the resonant cavity, the theory is proved that the reflectance is not only related to the back scattering of the reflectors, but also related to the relative position of them. The reflectance undulates as the relative position changed from one wavelength to two, which results in the periodic difference of the lock-in threshold. And the instability of the lock-in causes the bias of one frequency is different from the one nearby. Then, using the software of Matlab, some simulations are made to prove the theory. After that, a solution is proposed to decrease the bias difference.