Strong-field plasmonic electron acceleration with few-cycle, phase-stabilized laser pulses

We carried out experimental investigations on surface plasmon enhanced electron acceleration with few-cycle, carrier-envelope phase (CEP) stabilized laser pulses. We determined the spectrum of electrons accelerated in the plasmonic field and found that signatures of the phase stabilized optical waveform driving the individual electron trajectories are washed out in the electron spectra. We attribute this effect to nanoscale surface roughness of the metallic samples, as supported by extensive numerical simulations. This finding explains the previously observed, low CEP sensitivity of photoemission processes from metallic films and enables the development of femtosecond electron sources for ultrafast time-resolved applications.