A highly sensitive optical fiber temperature sensor based on the enhanced Vernier effect

A highly sensitive optical fiber temperature sensor based on enhanced Vernier effect is proposed in this paper. The sensor is a cascaded structure which is composed of fiber optic Sagnac interferometer (FSI) and intermodal Mach–Zehnder interferometer (IMZI). Because the interference fringes of the IMZI and the FSI shift to opposite directions as ambient temperature varies, the enhanced Vernier effect is obtained. Compared to the temperature sensor based on the traditional Vernier effect, the proposed sensor realizes the high sensitivity temperature measurement and doesn't need any special sensitizing materials, complicated manufacture process or a reference interferometer which need to be desensitized. Experimental results show that the sensitivity of the sensor is 20.86 nm/°C. A good linear responses can be obtained in temperature measurement range from 25 °C to 33 °C.