Optical fiber three-axis accelerometer based on lasers locked to π phase-shifted Bragg gratings

We report on a high-bandwidth, three-axis accelerometer developed with pi phase-shifted fiber Bragg gratings. The gratings are inserted into a cantilever system and interrogated by three separate telecom distributed-feedback diode lasers. The lasers are frequency locked to the sensors using a radio-frequency Pound-Drever-Hall technique. This scheme reduces the effect of laser amplitude noise and allows for real-time measurements with a dynamic range greater than 50 g. An operation bandwidth of about 1000 Hz is demonstrated with minimum detectable accelerations in the order of 10 mu g(rms) Hz (1/2) for frequencies above 10 Hz, only limited by the interrogating lasers frequency noise.