Drift of an optical fiber gyroscope caused by the Faraday effect: influence of the earth's magnetic field.

The drift of an optical fiber gyroscope caused by the earth's magnetic field through the Faraday effect is studied theoretically in a simple model and also in a practical model. The mechanism of its reduction using polarization-maintaining optical fiber is clarified; it depends on the twist and the birefringence of the fiber. The presence of the twist component whose period is just equal to one turn of the sensing fiber loop causes the drift; ways of suppressing it are described. Influence of the practical parameters, such as imperfection of the polarizer, is also discussed.