Surface-plasmon-enhanced MeV ions from femtosecond laser irradiated, periodically modulated surfaces

Enhanced emission of high energy ions is measured from sub-wavelength metallic grating targets under irradiation by intense (1015−1016 W cm−2), p-polarized, 50 fs, 800 nm laser pulses. The maximum ion energy is 55% higher and the ion flux is 60% higher for the modulated surface in comparison with polished surfaces of the same atomic composition. The ion emission, a result of enhanced light coupling and hot electron production in the grating targets, is correlated with enhancement in hard X-ray bremsstrahlung emission. The results are well reproduced by particle-in-cell simulations. The study reveals that the enhanced laser coupling by surface plasmon excitation on metallic gratings is directly responsible for the enhancement of ion energies