Energy exchange between colliding solitons in photonic crystal fibers.

Collisions of femtosecond solitons in silica core photonic crystal fibers are investigated experimentally and theoretically. Clear spectral signatures of the significant energy exchange between the interacting pulses are reported. Two primary and competing effects causing energy exchange are interpulse Raman scattering, which is insensitive to the phase difference of the colliding solitons, and the phase sensitive interaction via the Kerr nonlinearity.