Frustrated polarization fiber Sagnac interferometerdisplacement sensor

摘要

In an optical fiber Sagnac interferometer, a fiber coupler splits the light into two paths that are connected to the opposite ends of a fiber loop. Because the clockwise path and the anticlockwise path see the same environment, the interferometer is always balanced. For measuring rotation and displacement, we place a small loop of a calculated length in the fiber that causes the polarization to be different for the clockwise and anticlockwise paths, thus frustrating the interferometer and reducing the output signal by an amount dependent on the rotation of the small coil. The top of the coil is displaced sideways on rotation.