High precision measurement of the light polarization plane rotation angle

Sensors using tilted fiber Bragg gratings (TFBGs) are of great interest for researchers because of their high precision, compact size and resilience in harsh environments. However, the precision and reliability of the measurements made with them often depend on the polarization orientation. It is, therefore, necessary to control the rotation angle of the light polarization plane. Existing methods of measuring such an angle of light propagating in an optical fiber offer low measurement precision, require a long calibration process involving a human operator, or allow measurements only in narrow ranges of the rotation angle. In this study, we introduce a method of measuring the polarization plane rotation angle of light propagating in an optical fiber using two parallel TFBGs rotated relative to each other. The proposed method offers fully automatic calibration without human intervention and a greatly simplified calculation method. Our findings indicate that our method outperforms other methods in precision and reliability of measurement. The proposed method allows for measurements in the 0°-180° range with a mean absolute error of 0.064°.