Polarization-maintaining fiber-based optical coherence tomography for polarization-sensitive measurements

We present a polarization-maintaining (PM) fiber based optical coherence tomography system for polarizationsensitive and phase-sensitive measurements. Using a single detector, a single depth scan accurately yields retardance and polarization-insensitive reflectivity information along an A-line. Interference patterns on the orthogonal polarization channels are frequency multiplexed and extracted by digital band-pass filters. Images are insensitive to sample rotation in plane perpendicular to ranging. The use of PM-fibers allows direct calculation of birefringence without correcting the polarization transformations known in single-mode non-PM fibers. The system can be configured for differential phase measurements with minor modifications. In this case, a dual detector setup in the detection arm is used, and frequency multiplexing is not utilized.