Differential Phase-Shift-Keying Technique-Based Brillouin Echo-Distributed Sensing

In this letter, we experimentally demonstrate Brillouin echoes-based distributed optical fiber sensing with centimeter spatial resolution. It is based on a differential phase-shift-keying technique using a single Mach–Zehnder modulator to generate a pump pulse and a $pi$-phase-shifted pulse with an easy and accurate adjustment of delay. The results are compared to those obtained in standard Brillouin echo-distributed sensing system with two optical modulators and clearly show a resolution of 5 cm in a spliced segment between two fibers by applying a $pi$ -phase-shifted pulse of 500 ps.