Abstract

The propagation of light pulses in optical fiber permits the formation of solitons, either bright ones (anomalous fiber dispersion) or dark ones (normal dispersion). We have recently shown how a full ensemble of bright solitons can be generated. The experiment is straightforward: A train of picosecond pulses from a modelocked laser is launched into a piece of fiber. The fiber forms a ring resonator: light emerging from the distal fiber end is fed back into the proximal end, together with the external drive pulses. Since the resonator round trip time is adjusted to be synchronous with the repetition time of the drive pulses, there is interference between both contributions to the fiber input light. Pulse shaping in the fiber by dispersion and Kerr-nonlinearity in combination with this interference creates femtosecond substructure in the picosecond pulses. This substructure was identified as an ensemble of bright solitons [1]. Since solitons have mutual interaction (attractive or repulsive), there is a constant relative motion of all solitons in the ensemble so that the impression of a gas of particles is created (hence the name ‘soliton gas’ [1]), but under certain conditions, the solitons also form a regular array. The soliton gas is a unique test bed for the study of soliton interactions.

© 1998 IEEE