Fabrication of chirped and tilted fiber Bragg gratings on large-mode-area doubled-cladding fibers by phase-mask technique.

Abstract

We demonstrate here the inscription of chirped and tilted fiber Bragg gratings (CTFBGs), to the best of our knowledge, for the first time in hydrogen-loaded large-mode-area (LMA) double-cladding fibers using UV pulses and linearly chirped phase masks. High reflectivity wideband adjustable band-rejection filters are achieved in fibers like LMA-GDF-10/130-M and PS-GDF-20/400-M, with a wavelength coverage of more than 10nm and suppression ratio around 20dB. The spectrum and temperature properties are investigated. Experimental results indicate that CTFBGs could be used in double-cladding fiber systems with a smoothly varying attenuation spectrum and a low insertion loss, which is significant for further power scaling in a high-power fiber system.