Fabricating phase-shifted fiber Bragg grating by simple postprocessing using femtosecond laser

摘要

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 n phase shift at the central region of the grating and forms a n phase-shifted FBG. The procedure is simple, fast, and has good reproduc-tivity. 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.