Emission of Terahertz Pulses from Near-Critical Plasma Slab under Action of P-Polarized Laser Radiation

The theory of the terahertz (THz) waves emission from a near-critical plasma slab under the action of the focused p-polarized laser pulse is developed. The spectral, angular and energy characteristics of the THz signal are studied as functions of the focusing degree and the incidence angle of laser radiation, as well as the density and thickness of the plasma slab. It is shown that the extremely strong increase in the energy of the THz signal (up to millijoule level) and conversion rate (up to 10 %) occurs at the almost normal incidence of the ultra-short, tightly focused p-polarized laser pulse on the thin plasma slab with the near-critical density and rare electron collisions.