Wideband Remote-Sensing Based on Random Fiber Laser

Interrogating a remote passive-sensor with high fidelity is one of the biggest challenges in the sensing domain. Recently, random fiber laser (RFL) combined with remote fiber sensors was proposed for optical fiber sensing with high signal-to-noise ratio over ultra-long-distance fiber link. However, only quasi-static sensing has been demonstrated. In this work, a novel dynamic sensing scheme based on backward-pumped random fiber laser is proposed, and its sensing bandwidth is both theoretically and experimentally studied. Particularly, a Raman-gain-modulated power-balance model reveals that the RFL intensity has instantaneous and linear response to remote feedback disturbances, laying the ground for ultra-high-bandwidth sensing; in a proof-of-concept experiment, RFL with 100 km fiber and a far-end fiber Bragg grating is used for dynamic strain sensing, and 65 kHz dynamic sensing is achieved, the sensing bandwidth of which is two orders higher than that determined by the lightwave round-trip time as in the pulse-probing cases. This work paves the way for ultra-high-bandwidth and ultra-long-distance interrogation for optical fiber sensors.