Raman distributed temperature sensor based on pulse compression technique using hybrid modulation method

In this paper, a novel distributed Raman distributed temperature sensing system based on pulse compression technique using hybrid modulation method is proposed. The structure of the new system and the corresponding modulation and demodulation methods are described. The system performance is verified by experiments. This scheme solves the inherent problem of mutual restrictions between spatial resolution and temperature resolution existed in conventional Raman distributed temperature sensing systems. Compared with the other scheme not using coding, the hybrid modulation method using intra-pulse sweep and inter-pulse coding not only mitigates the transient effect existed in the fiber amplifier, which results in a better performance.