Laser frequency-noise-limited ultrahigh resolution remote fiber sensing

Abstract

When a fiber Fabry-Perot is used in an ultra-sensitive strain detection system via a radio-frequency interrogation scheme, its frequency discrimination properties can be enhanced by reducing the linewidth of its resonance. This increases the signal-to-noise ratio, and thus suppresses the strain equivalent noise floor. We demonstrate this improvement in a long-distance high performance remote sensing system and show that in reflection, it can mitigate the effects of random phase noise introduced by Rayleigh back-scattering. In transmission, it improves the remote system sensitivity to sub-picostrain resolution, which surpasses any other longdistance remote sensing system to date. With the reduced fiber Fabry-Perot linewidth, all noise sources in the delivery fiber become irrelevant, as the transmission system is limited only by the pre-stabilized laser frequency noise.