A method to fabricate fiber Bragg grating (FBG) in an optical microfiber (OM) from a conventional photosensitive fiber is proposed in this letter. The cladding of a conventional photosensitive fiber is etched to 17 μm. The etched fiber is drawn to an OM 6 μm in diameter. The photosensitivity of the fabricated OM is effectively reserved. A FBG in the OM (MFBG) is successfully fabricated using a KrF excimer laser at a fluence of 400 mJ/cm2 through a phase mask with a pitch of 1 089.3 nm. The reflectivity of the FBG is approximately 10%, and the 3-dB spectrum bandwidth is 0.13 nm. The concentration of brine is measured by immersing the MFBG in the liquid, and the minimum detectable refractive index variation can reach 7.2 × 10<sup>-5</sup> at a refractive index value of 1.33.
© 2013 Chinese Optics Letters
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(230.4000) Optical devices : Microstructure fabrication
(060.3738) Fiber optics and optical communications : Fiber Bragg gratings, photosensitivity
Fiber Optics and Optical Communications
Zhengtong Wei, Nuan Jiang, Zhangqi Song, Xueliang Zhang, and Zhou Meng, "KrF excimer laser-fabricated Bragg grating in optical microfiber made from pre-etched conventional photosensitive fiber," Chin. Opt. Lett. 11, 040603- (2013)