A dual-ended 400 km OFDR for vibration detection

Abstract

Abstract Optical frequency-domain reflectometer (OFDR) has been widely used in vibration detection because of its unique advantages of simple configuration and high spatial resolution. Based on remote fiber amplification, an unrepeated OFDR is experimentally investigated for vibration detection. To locate the vibration, we present an algorithm by calculating segmental cross-correlation between the beating signals with and without disturbances over the sensing fiber. It is shown that the OFDR demonstrates the ability of detecting the vibration over 222 km testing distance (112 km + 110 km). After sensing the first spool fiber of 112 km, the remnant laser is amplified by a remote-pumped erbium-doped fiber amplifier before proceeding to probe the vibration in the second spool one of 110 km. To be specific, the piezoelectric ceramic transducer-induced vibrations positioned at z = 110.9 km and z = 220.9 km are detected, respectively. More importantly, the OFDR system can be extended to operate in bi-directional sensing mode for the purpose of doubling the detection range, i.e. 400 km.