Abstract

Analogies between diffraction and dispersion are often used in optical science Both phenomena are concerned with the expansion of light, whether in the form of spatial beams or as temporal pulses They can be described with a similar physical picture, in terms of different phase accumulation for different (spatial or temporal) frequencies Dispersion is strongly material dependent, and is cancelled in vacuum and in certain materials at specific wavelengths. However, diffraction is mainly a geometrical phenomenon and depends only slightly on the medium of propagation Another important difference is the existence of two signs for temporal dispersion This gives the possibility of generating either bright or dark temporal solitons with the same sign of Kerr nonlinearity, simply working in two different dispersion regimes Conversely, diffraction always presents a negative dispersion of the spatial frequencies and hence, only bright spatial solitons are formed for a positive third order nonlinear index

© 2000 IEEE