Polarization-sensitive optical coherence tomography using polarization-maintaining fibers

Abstract

Optical Coherence Tomography (OCT) is a sensitive imaging technique that generates cross-sectional images of turbid tissues with a micrometer-scale resolution. Polarization-Sensitive (PS) OCT adds additional contrast to OCT by detecting polarization alterations within tissues, and provides accurate OCT images in polarization-altering tissues. Common approaches to build PSOCT are either: simple but difficult to incorporate in clinics and laboratories, or fiber-based and flexible but expensive, sophisticated, and computationally demanding. We have developed a new approach to build PSOCT using Polarization-Maintaining Fibers (PMF). A single depth scan is sufficient to calculate reflectivity, retardance, and axis orientation information using computationally-inexpensive algorithms. We present novel PMF-based PSOCT systems and demonstrate sensitivity figures larger than 100 dB, equivalent to common approaches. The developed PMF-based interferometers are used to measure minute Faraday rotations in tissue-mimicking phantoms, and the polarization properties of unmyelinated nerves. A novel algorithm is also developed to correct for errors calculating the birefringence of samples, and generate interpretable PSOCT images.