In development of the fiber optics resonant ring gyro it is important to measure the fiber ring linewidth to high accuracy. This short paper introduces a fast and accurate method for measuring of the resonator linewidth and its free spectral range. Using this technique polarization preserving fiber resonator with finesse of 1045 was measured.
"Ultra-High Finesse Polarization-Maintaining Fiber Resonator", Proc. SPIE 1169, Fiber Optic and Laser Sensors VII, (13 February 1990); doi: 10.1117/12.963056; https://doi.org/10.1117/12.963056