Analysis of polarization dependence of optical low coherence reflectometry using an active Faraday rotator

This paper analyzes the polarization dependence of the reflection signal from an optical low coherence reflectometer (OLCR) with an active Faraday rotator. I derive output signals from the OLCR at Faraday rotations of 0 and 90(degree), respectively, using unitary matrix representations of the states of polarization of the return and local oscillator lights. I investigate the polarization dependence of the reflection signal, defined as the sum of the two outputs, for different polarizer positions and show that polarization fading in the signal can be eliminated by placing the polarizer just before or after the Faraday rotator.