ANALYSIS METHOD OF ANISOTROPIC LIGHTGUIDE h -PARAMETER DEPENDENCE ON ITS BENDING RADIUS

The paper deals with the known methods for h-parameter measuring of the fiber and the new developed interferometry method. Analysis method of the anisotropic lightguide h-parameter dependence on its bending radius for the optical fiber is proposed. Micro bends of a fiber, being the defects of a sensitive element winding in a fiber-optic gyroscope (FOG), lead to the deterioration of a number of optical characteristics, in particular, the extinction coefficient and the cross-coupling coefficient. As a result, it worsens the FOG accuracy. The way of increasing the measurement accuracy and adaptation of the h-parameter measuring process to the existing technology of fiber-optic gyroscopes production is proposed. The mechanism of the polarization properties influence on the FOG accuracy is described through the analysis of secondary waves induced by the polarization transformation in the optical circuit. The influence estimation of the measured parameter on the FOG accuracy characteristics is given. For the gyro with the polarizer extinction coefficient equal to 27 dB, h-parameter 2·10-5 m-1, the length of the fiber loop 1500 m and the length of depolarization 4 mm the amplitude phase error does not exceed 3.2·10-5 rad and the intensity phase error is 2·10-10 rad.