In-situ method for removing refractive index chirp in fiber Bragg grating photo-written by Lloyd mirror

A novel method to reduce the index chirp of fiber Bragg gratings and improve the spectral response is proposed and demonstrated. The experimental layout includes a doubled Argon UV laser (244 nm) and an interferometric Lloyd mirror assembly mounted on a translation stage. The index chirp removing is achieved by a two steps UV radiation using the same gaussian laser beam and without removing the fiber from the set-up. First, we describe the two steps of the process to remove the unwanted refractive index chirp and second, we show the agreement between theorical and experimental results.