Complex space-time source-point method for propagation of a pulsed beam in slowly varying stratified media

The behavior of a pulsed beam is investigated in a plane-stratified medium. The beam is viewed as a field emerging from a complex space-time source point. Such a source radiates a directional field into real space-time. The transient (complex) ray field is evaluated through a multiple-reflection Bremmer-type analysis, taking the first term (the WKBJ term). Results are obtained through analytic continuation of well-known explicit expressions into complex-valued space-time source coordinates.