Fiber Ring Cavity Laser Based on Modal Interference for Curvature Sensing

Fiber ring laser sensor for curvature measurement based on a single-mode-no-core-single-mode structure is proposed and experimentally demonstrated. Compared with the conventional curvature system, the proposed laser sensor system has a high optical signal-to-noise ratio and a narrow 3-dB bandwidth, which enables the system to monitor the variation of micro-bending more distinctly. In the experiment, changes in peak wavelength show a blue shift when the curvature varies from 0.1225 to 0.4062 m
^-1
. The sensitivity of the curvature is about -22.33 nm/m
^-1
in the range of 0.2121-0.3463 m
^-1
. The response to the temperature of the fiber laser sensor is also discussed, where temperature sensitivity of 9.23 pm/°C within the range from 10 °C to 100 °C is obtained.