Long-range distributed temperature sensing with sub-meter scale spatial resolution based on BOTDA employing pre-pumped Golay coding

The BGS broadening caused by short pump pulse would degrade the SNR enhancement provided by the optical pulse coding and strongly reduce the measurement accuracy of coded BOTDA sensors, especially at long sensing ranges with sub-meter spatial resolution. In this work, to overcome this trade-off between spatial resolution and measurement accuracy, we implement a BOTDA sensor employing pre-pumped Golay coding with optimized pre-pumped pulse power. The proposed scheme fully exploits the SNR enhancement provided by the coding and the benefits from the pre-activated acoustic field established by the pre-pumped pulse, achieving distributed temperature measurements with 70 cm spatial resolution and temperature resolution better than 1.5 °C throughout the 50 km sensing fiber.