High-sensitivity temperature sensor based on single-mode fiber for temperature-measurement application in the ocean

A high-sensitivity and low-cost optical fiber sensor for seawater temperature sensing is designed and fabricated. The large core-offset splicing sensing structure was made of single-mode fiber only. To fabricate the sensing structure precisely with a length deviation <10 μm, the relative fabrication equipment was designed and assembled. Temperature measurement experiment of the sensor was performed in a seawater bath. Also, the experimental results show that redshift of the wavelength occurs with the increase of external temperature. Its temperature response curve conforms to the quadratic curve. The temperature sensitivity can reach up to 2.293 nm/°C, and the fitting degree is up to 0.9998. Moreover, the excellent repeatability of our sensor has been verified. The sensor has great potential to measure the temperature in the ocean.