Refractive Index and Temperature Sensor Based on Fiber Ring Laser With STCS Fiber Structure

A novel refractive index (RI) and temperature all-fiber ring laser sensor based on single-mode-tapered claddingless-single-mode (STCS) fiber structure is proposed and experimentally demonstrated. The STCS fiber structure acts as the sensing head and the filter of laser simultaneously. Thanks to the laser sensing system, high optical signal-to-noise ratio (
\(\sim 40\)
dB) and narrow 3-dB bandwidth (<0.12 nm) are achieved. For RI measurement, the average sensitivity reaches 163.80 nm/RIU in the RI range of 1.333–1.399. While for temperature measurement, a sensitivity of 10.8 pm/°C is achieved with the temperature ranging from 8 °C to 80 °C. The proposed system is simple and easy to construct, meanwhile, it shows the merits of high resolution, high signal-to-noise ratio and easier to monitor.