Experimental demonstration on 2.5m spatial resolution and 1oC temperature uncertainty over 74.6km BOTDA with combined Raman amplification and optical pulse coding

The combination of Raman amplification and optical pulse coding (OPC) is proposed to reduce the frequency uncertainty in long-distance BOTDA under higher spatial resolution. The experimental characterization of 74.6Km temperature sensing with measurement accuracy ~1oC under ~2.5m spatial resolution over the whole length of sensing fiber is demonstrated. The performance comparisons of BOTDA with purely Raman amplification and combined Raman amplification with OPC are also displayed.