Efficient and Reliable Optical Power Monitoring in Miniaturized Interferometric Fiber Optic Gyroscopes for Space Application

As the developing of interferometric fiber optic gyroscopes (IFOGs) in space, optical power monitoring has received considerable attention. However, adding additional measuring units is the main used method for optical power monitoring right now which is inconsistent with the development trend of high reliability, low cost, and miniaturization of IFOGs. This paper presents a novel approach to the optical power monitoring in IFOGs without increasing any devices. The demodulated signals detected by a photodetector to field-programmable gate array are analyzed. The inverse-demodulation method based on the characteristic analysis of the demodulated signals is proposed the first time to realize the optical power monitoring with a linear relationship. A simple and all-digital scheme is designed and implemented in the first closed loops of IFOGs with no effects on the rotation rate sensing. The optical power monitoring strategy is verified by a series of experimental results. The results show that its measuring accuracy is about 0.025 uw. The demonstrated repeatability is less than 0.065 uw. The proposed method is efficient and reliable, which will make it more suitable for space applications.