Isopropanol-sealed Cascaded-Peanut Taper fiber Structure for Temperature Sensing Incorporated Fiber Laser

In this paper, a new method for ultrasensitive temperature measurement is proposed and demonstrated. The sensor is based on two cascaded peanut structures to form a Mach Zehnder interferometer (MZI) in single mode fiber, and a cone is formed by repeat discharge in the interference region to enhance the evanescent field on its surface. At the same time, isopropanol with high thermal optical coefficient is filled for effective sensitization. The MZI was placed in a fiber ring cavity for filtering and temperature sensing. The results show that the fiber ring laser (FRL) has a narrower 3 dB band width (~0.15nm) and a high signal-to-noise ratio (SNR) (~50dB). In the temperature range of 20℃ to 50℃, the sensitivity reached -285 pm/℃. The sensor has the advantages of high sensitivity, simple structure and low cost. It is expected to be widely used in ocean temperature measurement.