Acceleration of electrons by tightly focused azimuthally polarized ultrashort pulses in a vacuum.

Using the complex sink-source model (CSSM) and the Hertz potential method (HPM), the electromagnetic field expressions of tightly focused ultrashort azimuthally polarized pulses can be obtained. By numerically solving the relativistic Newton-Lorentz equation, the acceleration and confinement of electrons by the sub-cycle and few-cycle azimuthally polarized ultrashort pulses in vacuum are studied. Considering the radiation reaction force, it is found that electrons with an initial kinetic energy of less than 1MeV can be accelerated to hundreds of MeV and can be confined in the range of less than 1 micron for hundreds of femtoseconds in the direction perpendicular to the pulse propagation (transverse direction) by the pulses.

Focusing characteristics of linearly polarized ultrashort pulses at the focal plane.

The dynamic focusing characteristics of linearly polarized ultrashort pulses are studied. Both the complex source-sink model (CSSM) and the Richards-Wolf diffraction integral theory (RWT) are used to study the focusing phenomena. For the central focus spot, the descriptions of both the CSSM and the RWT are well consistent.

Convergence and divergence focusing phenomena at the focal plane of ultrashort pulses.

Using the Richards-Wolf diffraction integral theory and the tightly focused ultrashort pulse vector model, the focusing phenomena at the focal plane of subcycle and few-cycle radially polarized ultrashort pulses are studied. The dynamic focusing is revealed at the focal plane. First, the subcycle or few-cycle ultrashort pulses shrink towards the focus.

Electron acceleration driven by sub-cycle and single-cycle focused optical pulse with radially polarized electromagnetic field.

The space-time properties of the expressions of sub-cycle and single-cycle focused optical pulses with radially polarized electromagnetic field based on the Sink-Source model are studied. The self-induced blue shift of the center frequency of spectrum in the center of the pulse field is found to have an important impact on the electrons acceleration. When the electrons approach to the center of pulse, the electrons will obtain a large kinetic energy gain in a short time.