Nonlinear systems introduce intriguing new wave phenomena. For example, the group velocity can be a function of ω, that is, group velocity dispersion occurs which leads to the shape of the envelope ...Nonlinear systems introduce intriguing new wave phenomena. For example, the group velocity can be a function of ω, that is, group velocity dispersion occurs which leads to the shape of the envelope of the wave packet being time dependent. As a consequence the group velocity in the wave packet is not well defined, and does not equal the signal velocity of the wave packet or the phase velocity of the wavelets.
