Resonant fiber-optic strain and temperature sensor achieving thermal-noise-limit resolution

In the area of fiber-optic sensors (FOSs), the past decade witnessed great efforts to challenge the thermal-noise-level sensing resolution for passive FOS. Several attempts were reported claiming the arrival of thermal-noise-level resolution, while the realization of thermal-noise-level resolution for passive FOSs is still controversial and challenging. In this paper, an ultrahigh-resolution FOS system is presented with a sensing resolution better than existing high-resolution passive FOSs. A fiber Fabry-Perot interferometer as the sensing element is interrogated with an ultra-stable probe laser by using the Pound-Drever-Hall technique. Both strain and temperature measurements are carried out to validate the performance of the sensor. The measured noise floor agrees with the theoretical thermal noise level very well. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

In the field of fiber-optic sensors (FOSs), significant efforts have been made in the past decade to challenge the thermal-noise-level sensing resolution for passive FOS. Although some claims have been made regarding achieving thermal-noise-level resolution, the realization of this resolution for passive FOSs remains controversial and challenging. This paper presents an ultrahigh-resolution FOS system with a sensing resolution surpassing existing high-resolution passive FOSs, utilizing a fiber Fabry-Perot interferometer as the sensing element and the Pound-Drever-Hall technique to interrogate it with an ultra-stable probe laser. Strain and temperature measurements are conducted to validate the sensor's performance, with the measured noise floor aligning well with the theoretical thermal noise level.