Fast Brillouin optical time-domain reflectometry using the optical chirp chain reference wave

A new technique for the fast implementation of Brillouin optical time-domain reflectometry has been proposed and demonstrated with the optical chirp chain (OCC) reference wave. By using the fixed bandpass filter and envelope detection, the spontaneous Brillouin spectrum can be online demodulated in the time domain for truly distributed, one-end access and fast measurement. The measurement time is only limited by the pulse repetition rate and averaging times. For a 400 m single-mode fiber, a 31.58 Hz strain vibration on a 2 m fiber segment is measured for a wide dynamic range (∼3200 µε) with an equivalent sampling rate of 200 Hz when 200 times of averaging is performed. Furthermore, the performance on the measurement accuracy is investigated with different OCC frequency spans and durations.