An Integrated Optical Fiber Sensor for Simultaneous Measurement of Temperature and Salinity Based on Sagnac Loop and TFBG

In this letter, we proposed and demonstrated a dual-parameter fiber sensor for simultaneous measurement of temperature and salinity based on Tilted Fiber Bragg Grating (TFBG) and Sagnac loop (SL). Thanks to the extremely high temperature sensitivity of polarization maintaining fiber (PM F) in SL, the designed sensor has a temperature sensitivity of 1.395 nm/°C. Besides, the temperature sensitivity of the core mode in TFBG is 0.009 m/°C and the sensitivity for salinity detection equals to 0.004 nm/% within the wavelength of cladding mode range from 1534 nm to 1535 nm, achieving the measurement of temperature and salinity concurrently. The designed temperature and salinity fiber sensor has certain potential in marine environmental detection.