Study of Ultra-Intense Laser Interaction with Oscillating Plasma Mirrors in the Radiation Pressure Dominated Regime

At laser intensities on the order of 10²²–10²³ W/cm², radiation pressure becomes the dominant mechanism governing the interaction between an ultra-intense electromagnetic wave and a dense plasma foil. The dynamical response of the plasma mirror depends sensitively on the incident laser intensity, the polarization of the electromagnetic field, and the density of the thin plasma layer; under appropriate conditions, the mirror motion may be treated as oscillatory. A solid, high-density plasma slab accelerated in the radiation-pressure-dominated (RPD) regime can efficiently reflect a counter-propagating, relativistically intense source pulse, leading to significant frequency up-shifting and the generation of high-order harmonics. Within this RPD framework, we present analytical and numerical investigations of the frequency spectrum, reflectivity, and brightness of radiation reflected from an oscillating plasma mirror.