In proximity side-writing fiber Bragg gratings (FBGs) using a phase shifted phase mask, the phase shift in the phase mask is split into two half-amplitude phase shifts. The effects of the phase-shift split on FBGs is investigated. A FBG with a split π-phase shift is modeled as two cascaded and tightly coupled grating-based Fabry–Perot filters. A compact expression of its reflectivity spectrum is obtained showing spectral asymmetry errors and a shift of the transmission peak. Our numerical results are in good agreement with previous experimental results. These effects decrease with increasing FBG length and become negligible for gratings more than a few millimeters long.
© 2006 Optical Society of America
Diffraction and Gratings
Original Manuscript: October 7, 2005
Revised Manuscript: February 27, 2006
Manuscript Accepted: March 9, 2006
Guillaume Tremblay and Yunlong Sheng, "Effects of the phase shift split on phase-shifted fiber Bragg gratings," J. Opt. Soc. Am. B 23, 1511-1516 (2006)