Comparative study on a core-offset fiber temperature sensor between the faraday rotation mirror structure and the double coupling structure

• A temperature sensor based on core-offset fiber and Faraday mirror is proposed.
• The problem of the instability and low sensitivity is solved.
• The maximum interference amplitude of FRM structure is significantly strong.
• Temperature sensitivity of the sensor is increased in an order of magnitude.

A temperature sensor based on core-offset single mode fiber (SMF) and a Faraday rotation mirror (FRM) has been proposed and experimentally demonstrated in this paper. This sensor was fabricated by splicing in a section of SMF between two SMFs with a core-offset at two splicing joints. The end of the joint is connected to the FRM, which can double the sensitivity and improve the polarization state stabilization at the sensor output. The variation of the transmission spectrum of the sensor with respect to the surrounding temperature has been experimentally studied. A comparison is made between this design and a laser temperature sensor made of the same core-offset fiber utilizing a double coupling (DC) structure. The results show that, within the range of 1539.42–1553.90 nm, the sensitivity of the proposed sensor is 0.89039 nm/°C and in the range of 47–63 °C. Additionally, the power attenuation is 2.257 dB/°C. The temperature sensitivity in the SMF and FRM sensor is increased by an order of magnitude in comparison with the DC sensor. The instability and low sensitivity characteristics of a laser temperature sensor constructed with DC structure can be solved through the use of core-offset SMF and FRM.