High-quality fiber Bragg grating inscribed in ZBLAN fiber using femtosecond laser point-by-point technology

We demonstrate for the first time, to the best of our knowledge, the fabrication of a high-quality fiber Bragg grating (FBG) in ZBLAN fiber by using an efficient femtosecond laser point-by-point technology. Two types of FBG, e.g., high coupling coefficient and narrow bandwidth grating, are successfully obtained. The coupling coefficient is strongly dependent on the grating order and pulse energy. A second-order FBG with an ultrahigh coupling coefficient of 325 m −1 and reflectivity of 97.8% is inscribed in the ZBLAN fiber. A pair of FBGs with a narrow FWHM of 0.30 and 0.09 nm are also demonstrated.