The Third Closed-Loop Control for Compensating Light Power Fluctuations in the Interferometric Fiber-Optic Gyroscope

In the interferometric fiber-optic gyroscope (IFOG), the stability of the light source is crucial. The fluctuations of light source power (LSP) do greatly compromise the performance of IFOG. When the driving current of the light source has fluctuations of about 0.5 to 2 mA, the bias stability of the gyroscope becomes 2 to 3 orders of magnitude worse. However, simplifying the light source is an important step in the process of miniaturizing and lowering the costs of IFOG, which compromises the stability of the light source and leads to fluctuations of the LSP. Therefore, it is important to compensate for fluctuations of the LSP. Earlier we have found that the differential signal of LSP was always crosstalked into the output signal of IFOG, under the prerequisite that the feedback phase could completely neutralize the light-intensity difference of the last period. We have given a solution to this case in our previous research work, but the prerequisite is not satisfied in many cases, and the crosstalk in the gyroscope is no longer the differential signal of LSP. In this paper, we propose a novel closed-loop control to solve this problem. The experimental results prove that this new method can effectively reduce the impact of LSP fluctuations by about 95%.