Light bullet
Light bullets, predicted and so termed in 1990 (The Collapse of Optical Pulses, Y. Silverberg), later demonstrated the following decade ,[1] are localized pulses of electromagnetic energy that can travel through a medium and retain their spatiotemporal shape in spite of diffraction and dispersion which tend to spread the pulse. This is made possible by a balance between the non-linear self-focusing and spreading effects brought about by the medium in which the pulse beam propagates.[2]
Comparison with solitons
Spatial and temporal stability which are the characteristics of a soliton have been achieved in light bullets using alternative refractive index models. An experiment which exploited the discrete spreading and self-focusing effects on 170-femtosecond pulses at 1550-nanometre wavelengths by a two-dimensional hexagonal array of silica waveguides reported a spatial profiles stationary for about twice as far as it would be in linear propagation and temporal profile about nine times stationary as that of the corresponding linear propagation.[3]
Light bullets lose energy in the process of a collision. This behavior is different from that of solitons which survive collisions without losing energy[4]