Temperature Sensor Employed TCF-PMF Fiber Structure-Based Sagnac Interferometer

A cost-efficient all fiber temperature sensor based on a Sagnac interferometer is proposed and experimentally demonstrated. The sensor proposed comprises a section of thin core fiber (TCF) in combination with Panda type polarization maintaining fiber (PMF). The key point is that the core of TCF is intentionally aligned to one of two stress areas of Panda type PMF in order to change the mode transmission. Then the prepared TCF-PMF fiber structure is built into a Sagnac loop. A well-defined spectrum is obtained and the fringe contrast reaches up to 28 dB. The dip wavelengths are employed to demonstrate the temperature characteristics. The experimental results show the transmission spectrum blue-shift with the temperature and sensitivity of -1.54 nm/°C is obtained. The proposed sensor has potential application in temperature measurement.