Attosecond phenomena in the relativistic λ³ regime

Modeling of relativistically strong laser pulses interacting with overdense plasma targets indicates that coherent motion of electrons leads to the generation of strong attosecond electromagnetic pulses and dense attosecond electron bunches [N. Naumova et al., Phys. Rev. Lett. 92, 063902 (2004); ibid. 93, 195003 (2004)]. Particle-in-cell simulations predict that optimal conditions for these attosecond phenomena are achieved in the λ³ regime, when few-cycle laser pulses are focused to a wavelength-limited spot, producing maximal intensity and maximal gradients with a given energy. The natural synchronism of these attosecond phenomena should enable relativistic attosecond optoelectronics. First experiments toward verification of attosecond pulse production confirm a basic element of attosecond pulse generation-relativistic deflection.