Millimeter-level recognition capability of BOTDA based on a transient pump pulse and algorithm enhancement

Brillouin optical time-domain analysis requires a pulsed pump to obtain a distributed Brillouin gain spectrum (BGS) containing environmental information, whose width corresponds to spatial resolution (SR). We propose a rising edge demodulation (RED) algorithm acting on Brillouin information generated by a transient pump pulse (<phonon lifetime) via a nonlinear weight matrix to enhance SR. The distributed BGS generated by using an 8-ns transient pump pulse is processed by the RED algorithm, and its SR is enhanced from 0.8 m to 1 mm (i.e., 800-fold improvement) in the simulation and 8 mm (i.e., 100-fold improvement) in the experiment.