Least square fitting demodulation technique for the interrogation of an optical fiber Fabry-Perot sensor with arbitrary reflectivity.

A novel Fabry-Perot (F-P) demodulation technique based on least square fitting for arbitrary reflectivity F-P sensors is proposed. The demodulation method was simulated and analyzed to verify feasibility of the algorithm. Two different finesse F-P interferometers constructed with a reflector bracket were used to make the stability experiments and the stepping experiments. The results show that the demodulation technique can interrogate the cavity length of F-P interferometers with different fineness in a wide range, and the demodulation error is less than 12 nm.