Suppression of cladding mode coupling loss in fiber Bragg gratings

We have demonstrated, for the first time, the suppression of cladding mode coupling loss to similar to0.1 dB in 30-dB fiber Bragg gratings for both no nhydrogenated and hydrogenated fibers. These fibers have also been optimize d to give 0.04-dB average splice loss to SMF-28 fiber. The suppression of c ladding mode coupling is achieved by accurately characterizing and controll ing the photosensitive profile. This low level of cladding mode coupling lo ss has opened up a new range of broadband applications, previously restrict ed by the limited free spectral range of fiber Bragg gratings.