Studies on Some Aspects of Light Beam Propagation Through ...

Spatio-temporal soli tons
• Transitive nonlinearities
In this kind of nonlinearity, the refractive index transits from one
functional form to another as intensity increases. Such nonlinearity
was used in the case of bistable soli tons. A simple model for the
transitive nonlinearity has the form
1.1.3 Spatia-temporal solitons
9
(1.19)
When both the spatial and temporal effects are present together, we get
a different entity called the spatia-temporal soli tons or the "light bullets" .
The word was first coined by Silberberg. 16 Spatia-temporal soli tons are
packets of wave which are confined in all three dimensions (two transverse
dimensions and one time dimension) while propagating. The effect of
dispersion and diffraction is simultaneously present and is compensated
by the nonlinearity of the medium.
x
Figure 1.3: Schematic diagram of formation of a spatiotemporal soli ton
due to the simultaneous balance of diffraction and dispersion by nonlinear
self-focusing. 17