Achieving 30-cm spatial resolution over 6.0 km in Raman distributed optical fiber sensing using chaotic pulse cluster demodulation

The principle of optical time-domain reflection localization limits the sensing spatial resolution of Raman distributed optical fiber sensing. We provide a solution for a Raman distributed optical fiber sensing system with kilometer-level sensing distance and submeter spatial resolution. Based on this, we propose a Raman distributed optical fiber sensing scheme based on chaotic pulse cluster demodulation. Chaotic pulse clusters are used as the probe signal, in preference to conventional pulsed or chaotic single-pulse lasers. Furthermore, the accurate positioning of the temperature variety region along the sensing fiber can be realized using chaotic pulse clusters. The proposed demodulation scheme can enhance the signal-to-noise ratio by improving the correlation between the chaotic reference and the chaotic Raman anti-Stokes scattering signals. The experiment achieved a sensing spatial resolution of 30 cm at a distributed temperature-sensing distance of ∼6.0 km. Furthermore, we explored the influence of chaotic pulse width and detector bandwidth on the sensing spatial resolution. In addition, the theoretical experiments proved that the sensing spatial resolution in the proposed scheme was independent of the pulse width and sensing distance.