Temporal focusing of composite X-waves transmitted through a planar surface of discontinuity

A scheme is introduced for focusing pulses generated in one medium at a position in a second medium. The analysis is carried out for the general case of oblique incidence on a planar interface separating the two media. This method depends on constructing a composite pulse from a train of X-waves traveling at different speeds. The initial temporal separation between the individual X-waves is chosen such that the resulting field is focused underneath a surface of discontinuity separating two different media.