Distributed temperature sensing based on slope‐assisted Brillouin optical correlation‐domain reflectometry with over 10 km measurement range.

The authors demonstrate distributed temperature sensing based on slope‐assisted Brillouin optical correlation‐domain reflectometry (BOCDR) with a long measurement range of >10 km. They find that to achieve such a long‐range measurement, a delay line in a reference path needs to be at least four times longer than the sensing fibre. In addition, they show that the use of such a long delay line induces forward‐propagating Brillouin‐scattered light in the reference path, which deteriorates the signal‐to‐noise ratio (SNR) of the system and should be suppressed. Finally, by exploiting a beyond‐nominal‐resolution effect of the slope‐assisted BOCDR, they detect a 3‐m‐long heated section in a 13‐km‐long silica fibre in a distributed manner; the reason for its low SNR is also discussed. [ABSTRACT FROM AUTHOR]