A temperature fiber sensor based on tapered fiber Bragg grating fabricated by femtosecond laser

Abstract

A temperature fiber sensor based on tapered fiber Bragg grating (tapered FBG) fabricated by femtosecond laser has been proposed and realized with good reproducibility. Firstly, the fiber taper with 25 μm diameter and 1000 μm length is fabricated by arc-discharge elongation using two standard single-mode fibers. Secondly, two first-order FBGs are fabricated in tapered and non-tapered fiber regions for comparison. Both FBGs are point-by-point direct-written by femtosecond laser, and the grating lengths are 1000 μm. Thirdly, a temperature experiment is performed using a heating chamber, and experimental results show that in the range of 30~350 °C, the temperature sensitivity of the tapered FBG has increased from 11.0 pm/°C to 12.3 pm/°C. The tapered FBG proposed here can be further configured for sensing other parameters in physical, chemical, and biomedical applications.