  We propose a method to generate femtosecond, relativistic and high-charge
electron bunches using few-cycle and tightly focused radially polarized laser
pulses. In this scheme, the incident laser pulse reflects off an overdense
plasma that injects electrons into the reflected pulse. Particle-In-Cell
simulations show that the plasma injects electrons ideally, resulting in a
dramatic increase of charge and energy of the accelerated electron bunch in
comparison to previous methods. This method can be used to generate femtosecond
pC bunches with energies in the 1-10 MeV range using realistic laser parameters
corresponding to current kHz laser systems.
