High-birefringence fiber-optic polarimeter with submicroradian phase delay detectability

The performance of a fiber-optic polarimetric sensor is characterized. The polarimeter is constructed from 50 m of high-birefringence bow-tie fiber. Quadrature is maintained with the phase tracking dc technique. A 90° splice at the fiber midpoint provides optical common mode rejection. Minimum detectable rms phase delays below 1.0 μrad in a 1-Hz bandwidth are readily achievable at frequencies greater than 5.0 kHz. This compares well with shot noise estimates for the rms phase delay fluctuations.