Abstract
The motion of a wave packet in a nonuniform medium is discussed. It is found that the wave-packet motion, obtained by WKB method, is the same as one obtained by geometrical optics. The wave packet, in general, undulates around the axis. As the direction of the beam and the local refractive index change as the packet travels, the axial velocity component of the beam is modulated. This seems to be in contradiction to the constancy of the group velocity. This apparent contradiction is eliminated by examining the shape of a wave packet composed of a single transverse mode, which turns out to be warped. As an example, a medium is assumed in which the dielectric constant decreases quadratically, away from some spatial axis. The group velocity of several undulating packets in the medium is very close to that of a straight ray. Numerical calculation is presented.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
