Fast Brillouin optical time domain analysis utilizing double-sideband digital optical frequency comb

We propose and demonstrate a fast Brillouin optical time domain analysis (BOTDA) based on simultaneous measurement of Brillouin gain spectrum (BGS) and Brillouin loss spectrum (BLS) with double-sideband digital optical frequency comb (DOFC). By using the two sidebands of DOFC probe to interrogates the BGS and BLS, respectively, simultaneous acquisitions of BGS and BLS with a fixed frequency difference are achieved by direct detection without sideband selective optical filters. The measurement accuracy of the system is significantly improved compared to traditional single-sideband based schemes without increasing the system complexity. Eventually, the proposed BOTDA sensor achieves less than 1-MHz frequency uncertainty over 10-km fiber with a 20-m spatial resolution, and 5.5-ms measurement time. The experimental results validate that the proposed high-performance scheme is very promising for distributed dynamic sensing application.