The method of fabricating phase-shifted fiber Bragg grating (PSFBG) that does not need a phase mask by femtosecond laser (fs) post-processing is demonstrated. A central region of standard single mode fiber Bragg grating (FBG) is irradiated by fs laser. A rotating jig is designed to hold and rotate the fiber when the fiber is irradiated by laser. The bandwidth of transmission peak of PSFBG and the transmission loss is growing with increasing of laser energy. PSFBG produced by this method is simple, fast and reproducible.
Fabricating of phase-shifted fiber Bragg grating (PSFBG) by a femtosecond (fs) laser postprocessing of standard single mode fiber Bragg grating (FBG) without phase mask is demonstrated. A central region of grating is irradiated by an fs laser assisted with a rotating jig, which produces a π phase shift at the central region of the grating and forms a π phase-shifted FBG. The procedure is simple, fast, and has good reproductivity. The bandwidth of transmission peak of PSFBG grows with an increasing amount of laser energy or length of irradiation and decreasing of translation speed; the transmission loss decreases with increasing irradiation length. Additionally, the repeatability of fs postprocessing and temperature stability of PSFBG were investigated.