Investigation of Temperature Sensing Performances Based on an Aluminized Panda Polarization Maintaining Fiber With a Fiber Bragg Grating in Sagnac Loop

The polymer coating on the surface of traditional optical fiber would deform and melt at high temperature. Metal coating which could maintain its shape in a large temperature scale is one solution to this problem. In this work, we experimentally investigated the temperature sensing performances based on an aluminized panda polarization maintaining fiber (APPMF) and a fiber Bragg grating (FBG) in Sagnac loop in a large temperature scale. Modeling simulation of APPMF proved that its birefringence was influenced by temperature and it could be used as the temperature-sensing probe in an SI. FBG was used to mark the dip wavelength in SI when the movement of dip wavelength exceeded a free spectral range (FSR). Experimental results showed that the maximum sensitivity reached 0.818 nm/°C for a 12 cm long APPMF, while increased to 1.011 nm/°C as the length of APPMF decreased to 2 cm. The aluminum coating enhanced the ductility of the fiber and made the fiber suitable for high-temperature measurement. The proposed APPMF also experienced a degradation because of germanium diffusion in fiber core very high temperature which made the sensor suitable for very high temperature sensing in a short time. This work provides a useful attempt for exploring high-temperature fiber interferometric sensing.