Direct acceleration of electrons by intense ultrashort laser pulses

A fundamentally new mechanism of laser-driven acceleration of charged particles is proposed. When intense, tightly focused ultrashort laser pulses are employed, the acceleration is determined by the light pressure force and the longitudinal electric field component, which can be unidirectional. It is shown that lasers with ultimately high (present-day) parameters can accelerate electrons up to energies ~1 GeV, which is comparable to energies attainable in 'large' accelerators. In this case, the acceleration (unlike the schemes considered in the literature) is insensitive to the initial field phase, the acceleration of slow electrons is possible, and the problem of extraction of accelerated electrons from the field is solved.