Femtosecond laser pulses inscribed EFBG and its sensing characteristics

Abstract

In this paper, we presented the inscription and sensing characteristics of eccentric fiber Bragg gratings (EFBGs) through femtosecond laser. This kind of fiber grating is caused by localized refractive index modulation that deviates from the center of the fiber core. EFBGs were prepared in SMF-28 single-mode fiber by 800nm femtosecond laser point-by-point writing method. The temperature and refractive index sensing properties of the prepared EFBG were investigated. The experimental results show that both the Bragg wavelength and cladding mode resonance wavelength of EFBG increase linearly with temperature and show extremely high-temperature robustness. The temperature sensitivity of Bragg resonance is 14.4 pm/℃. As the SRI increases, the Bragg peak remains unchanged and the cutoff wavelength of EFBG cladding mode resonance red-shifts with a sensitivity of 649.29 nm/RIU.