Ponderomotive electron acceleration by polarization-gated surface-enhanced optical fields

We study ponderomotive electron acceleration with polarization-gated surface-plasmon-resonance enhanced optical fields excited by two counter-incident femtosecond laser pulses. Such a polarization-gated excitation scheme creates an intense linearly polarized high-gradient evanescent field for electron acceleration. The maximum kinetic energy of the accelerated ultrafast electrons is doubled with a symmetric angular distribution about the normal of the metal surface as compared with the conventional one-pulse excitation scheme.