Ablation of Clusters from Surfaces for Harmonic Generation of Laser Radiation

Abstract

In this Chapter, we show the results of systematic experimental studies of the ablation of the surfaces containing fullerenes and high-order harmonic generation in C60-rich laser-produced plasma under different plasma conditions and laser parameters. The morphology of fullerene clusters before and after ablation is analyzed to define the optimal conditions of excitation of C60-containing surfaces. The enhancement of high-order harmonic generation efficiency in C60-rich plasmas by using the two-color pump technique is discussed. The conversion efficiency for the odd and even harmonics in the vicinity of surface plasmon resonance of the C60-containing plasma (40–70 nm) was estimated to be in the range of 10−4. We also discuss the high-order harmonic generation during ablation of nanoparticle-containing targets using a high pulse repetition rate lasers and on the relation of the harmonic signals with the morphological and spectroscopic characteristics of the ablation deposits. The study of the deposits has allowed the definition of ablation conditions leading to the generation of a plasma containing nanoparticles of similar sizes to the ones used as target material. The corresponding plasma plumes lead to efficient conversion of the infrared photons towards the short-wavelength range through high-order harmonic generation and show superior performance than those corresponding to bulk targets of the same metallic element.