Endogenous BOTDA in the self-homodyne coherent detection transmission system for communication-integrated datacenter temperature monitoring

This Letter demonstrates the high compatibility of the self-homodyne coherent detection (SHCD) transmission system with the Brillouin optical time-domain analyzer (BOTDA). By fully utilizing the remote delivered local oscillator (LO) light of the transmission system, the first, to the best of our knowledge, endogenously integrated BOTDA subsystem is achieved. The remote delivery of the homologous laser source in the SHCD system ensures the frequency match between the probe light and the pump light of the BOTDA. Furthermore, an injection-locked distributed feedback (DFB) laser is employed to amplify the LO and eliminate the impact induced by the Brillouin gain. The experiment demonstrates that a 16-km distributed temperature sensing based on BOTDA can be insensibly emerged into a 50-Gbaud DP-16QAM SHCD transmission system (400 Gbps/λ/core), achieving a spatial resolution of 3 meters and a temperature accuracy of 1°C. Remarkably, the auxiliary sensing module has negligible impact on the transmission.