Study on polarization state in depolarized fiber optic gyroscope

The instability of polarization state in interference fiber optic gyroscope (FOG) restricts the precision and stability of FOG. There are two methods to increase FOG's precision and stability, that is, to maintain or eliminate the state of polarization in fiber. Using Lyot fiber depolarizer not only reduces the effects of the states of polarization on the performance of FOG, but decreases the cost of FOG to a large extent, which is quite suit for the medium and low precision FOG. This article analyzes the principle of Lyot fiber depolarizer and the interchangeable character of input and output ports, deduces the structural parameters of Lyot fiber depolarizer and discusses the effects of parameters on the depolarizer's performance with Jones matrix. What's more, polarization transformation and polarization errors in depolarized fiber optic gyroscope (DFOG) are discussed in detail. Experimental result shows that the depolarizer we designed is very effective to reduce the drift of FOG, and depolarized fiber optic gyroscope is suit for fields using medium precision FOG. The analysis provides academic guidance to depolarizer used in depolarized fiber gyroscope or other fiber optic sensors.