Effects of Laser Intensities and Target Shapes on Attosecond Pulse Generation from Irradiated Solid Surfaces

Single attosecond pulses can be generated when an intense laser pulse focused in a volume of a few cubic wavelengths (λ³) is reflected from a solid plasma surface. With relativistic two-dimensional particle-in-cell simulations, we investigate the effects of the incident laser intensity and the target surface profiles on attosecond pulse generation. Usually the width of the reflected attosecond pulse decreases and its electromagnetic energy density increases with increasing laser intensity, while the energy conversion efficiency to the attoseond pulse decreases. By changing the target surface profile, such as using a convex surface or adding proper preplasma, one can further shorten the attosecond pulse duration and meanwhile increase its energy density.