Birefringence measurement in optical fibers by polarization-optical time-domain reflectometry

The technique of polarization-optical time-domain reflectometry is analyzed to see how the polarization properties of an optical fiber may be deduced from the backscattered light. It is shown that, subject to certain assumptions, the polarization is modified as it would be by a linear retarder. The results of measurements on a fiber showing both linear and circular retardation are given and compared with a theoretical model. The experiments show that the accuracy of measurement is limited by changes in the polarization, due to the scattering process, which vary randomly along the fiber.