High-order harmonic generation of picosecond radiation of moderate intensity in laser plasma

The results of investigations into the generation of highorder harmonics (up to the 21st order) of picosecond (τ = 38 ps) Nd : YAG laser radiation in the plasma produced by laser ablation of metal and carbon-containing material surfaces are presented. We demonstrate the feasibility of generating high-order harmonics in the vacuum ultraviolet spectral range (with radiation wavelengths shorter than 120 nm) in plasmas with an efficiency of ~0.7 × 10^-4. In carbon-containing plasma, the 7th harmonic intensity exceeded that of the 5th one by a factor of seven.