A Long-range Fiber-optic Raman Distributed Temperature Sensor Based on Dual-source Scheme and RZ Simplex Coding

We proposed a novel cost-effective Raman distributed temperature sensor (RDTS), where two directly modulated distributed feedback (DFB) laser diodes were employed to mitigate transient effect when pulse sequences are amplified by Erbium doped fiber amplifier (EDFA). Moreover, return-to-zero (RZ) Simplex codes and complementary RZ Simplex codes were modulated on the two DFB lasers so as to improve signal-to-noise ratio (SNR) and temperature resolution. Without using any modulators, a spatial resolution of 10 m over 56-km optical fiber, and a temperature resolution of 1.8 °C at the positon of 50 km were demonstrated by using the proposed technique.