Adaptive Fiber Ring Laser Based on Tapered Polarization Maintaining Fiber in Sagnac Loop for Temperature and Salinity Sensing

An optical fiber ring laser (FRL) cavity-based sensitive temperature and salinity sensor is proposed experimentally demonstrated. The consists of a Sagnac loop with waist 15 µm total length 30 cm made tapered polarization-maintaining (PMF). dual parameter sensing was theoretically modeled presented. sensitivity 0.173 nm/‰ possible by the efficient interaction between PMF cladding mode external refractive index. In addition, 0.306 nm/°C achieved through ultrahigh birefringence PMF. Apart from that, previous system used broadband light source (BBS) as input light, resulting in wide bandwidth poor signal-to-noise ratio (SNR). integrated into FRL can achieve high SNR approximately 50 dB narrow 0.15 nm while serving filter head. Additionally, developed has advantages simple design, low cost, easy fabrication. It also extend distance indefinitely within given range, which anticipated to have positive effects on testing marine environments laboratories.