Grating-Outcoupled Radiation in Second-Order Fiber Bragg Gratings

The experimental results of the radiation for second-order fiber Bragg gratings, which are made of a single-mode photosensitive fiber (PS-1500; Fiber-Core Corp.) and a single-mode fiber (SMF-28; Corning Inc.), by a phase mask writing fabrication technique are explored. For PS-1500 fiber Bragg gratings, the maximum radiation efficiency of -23.5 dB at resonance lambda = 1,539.34 nm with a very narrow bandwidth (about 0.02 nm) are measured from a 10-mm-diameter photo-detector, while for SMF-28 fiber Bragg gratings, the maximum radiation efficiency is -34.6 dB (lambda = 1,538.03 nm) with a bandwidth of 0.06 nm. The total efficiencies of the radiation are about -16.8 dB for PS-1500 fiber Bragg gratings and -28.1 dB for SMF-28 fiber Bragg gratings.