Long-range high-spatial-resolution distributed Brillouin sensing enabled by correlation-domain encoding.

A hybrid aperiodic-coded Brillouin optical correlation domain analysis (HA-coded BOCDA) fiber sensor is proposed to achieve long-range high-spatial-resolution distributed measurement. It is found that high-speed phase modulation in the BOCDA actually forms a special energy transformation mode. This mode can be exploited to suppress all detrimental effects parasitized in a pulse coding-induced cascaded stimulated Brillouin scattering (SBS) process and thereby enable the HA-coding to reach its full potential to improve the BOCDA performance. As a result, under a low system complexity and an enhanced measurement speed, a 72.65-km sensing range and a 5-cm spatial resolution are achieved with a temperature/strain measurement accuracy of 2℃/40 με.