Phase-coded Brillouin optical correlation domain analysis with 2-mm resolution based on phase-shift keying.

Abstract

We report a phase-coded Brillouin optical correlation-domain analysis (BOCDA) based on phase-shift keying (PSK), in which the pseudo-random binary sequence (PRBS) phase coding is realized using a Mach-Zehnder modulator (MZM). Unlike the conventional phase-coded BOCDA using a phase modulator, which suffers from the non-rectangular transition in the encoded phase, the PSK can realize perfect phase switches between 0 and π with zero-width edges. It is not sensitive to the bandwidth of the modulator and the power of the radio-frequency modulation signal. Numerical simulations and experimental results prove that it can effectively suppress the Brillouin amplification in the off-peak positions. In experiment, a 2-mm spatial resolution sensing is realized using only a 20-GHz bandwidth MZM.