Raman-based distributed temperature sensor with 1 m spatial resolution over 26 km SMF using low-repetition-rate cyclic pulse coding

We experimentally investigate the benefits of a new optical pulse coding technique for long-range, meter and submeter scale Raman-based distributed temperature sensing on standard single-mode optical fibers. The proposed scheme combines a low-repetition-rate quasi-periodic pulse coding technique with the use of standard high-power fiber lasers operating at 1550 nm , allowing for what we believe is the first long-range distributed temperature measurement over single-mode fibers (SMFs). We have achieved 1 m spatial resolution over 26 km of SMF, attaining 3°C temperature resolution within 30 s measurement time.