Subcycle Pulsed Focused Vector Beams

An accurate description of a subcycle pulsed beam (SCPB) is presented based on the complex-source model. The fields are exact solutions of Maxwell's equations and applicable to a focused pulsed beam with a pulse duration down to and below one cycle of the carrier wave and with arbitrary polarization state. Depending on the pulse duration, the pulse is blueshifted, and its wings are chirped. This effect, which we refer to as "self-induced blueshift" goes beyond the carrier-envelope description. The corresponding phase is a temporal analog of the Gouy phase. The energy gain of a relativistic electron swept over by an SCPB is very sensitive to the proper form chosen to describe the pulse.