Investigation of mode coupling effects on sensitivity and bias of a multimode fiber loop interferometer: Application to an optimal design of a multimode fiber gyroscope

We report the analysis of mode coupling effects on performances of fiber optic gyroscopes (FOG) based on multimode fiber loop interferometer (MFLI). The advantage of using such fiber type is to develop a low-cost FOG dedicated to medium performances applications. The analysis is performed by modeling the operation of a multimode fiber optic gyroscope (MFOG) using matrices representation of its optical components. The main results show that the multimode interferences occurring at the output of such device yields a stable output due to the averaging effect over the modes. However, the presence of coupling between modes degrades its performances, such as sensitivity and bias stability. Finally, we demonstrate that an optimal choice of the MFOG optical components, in particular the multimode fiber, can lead to an attractive solution according to the compromise price/performances.