Nonlinear propagation in long fibre Bragg gratings

We have presented experimental evidence of nonlinear propagation in fibre Bragg gratings of differing lengths. For the 20 cm grating we obtain excellent switching and observe the formation of multiple gap solitons. These results are also in agreement with our numerical modelling although much work needs to be done to accurately model the system and to properly decouple the pulse formation and propagation effects. For the case of the 40 cm gratings the results obtained are much harder to interpret due to the presence of stimulated Brillouin scattering in the system. This reduced the amount of coupled light into the grating at high power to a level below that necessary to see multiple soliton formation although we could still see the formation of a single soliton which is far broader than those in the 20 cm grating