Strong fiber Bragg grating fabrication by hybrid 157- and 248-nm laser exposure

Abstract

A permanent 248-nm photosensitivity response was locked into hydrogen-loaded standard telecommunication fiber by uniform 157-nm F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -laser pre-exposure. Strong (>30 dB) fiber Bragg gratings were efficiently generated after hydrogen out-diffusion, improving the thermal stability. The 157-mn radiation produced weakly absorbing Si-OH and Ge-OH absorption bands at 1.39-μm.