High-order harmonic generation in the laser-induced plasmas produced on the surfaces of transition metals (Rh, Ru, Nb, and Zr) from the fifth period of the periodic table

Abstract

The plasmas produced on the surfaces of the transition metals from the fifth period of the periodic table (Rh, Ru, Zr, and Nb) were used for the high-order harmonic generation of 65 fs, 802 nm pulses. This process was performed by choosing the optimal delay between heating and driving pulses, the distance from the target to the propagating femtosecond pulses, and the fluence of heating pulses. The resonance enhancement of single harmonic, two-color pump-induced harmonic generation and application of near-infrared pulses for sum and difference frequency generation are reported. The harmonic cutoffs up to 19th, 29th, 39th, and 43rd orders were observed from the Rh, Ru, Zr, and Nb laser-induced plasmas. The comparison of the resonance enhancement of harmonics in different plasmas containing the elements of the fifth period is presented.