Interaction of an Intense Laser Beam with Anharmonic Clusters and Resonant Third Harmonic Generation

This model investigates the third harmonic generation (THG) of a laser beam in nanoclustered plasma. The interaction of a highly intense laser beam with Argon nanoclusters results in the displacement of electrons in the medium. The interaction gives rise to a restoring force that depends nonlinearly on the electron excursion, causing anharmonic oscillation of the electron clouds within the clusters. To ensure resonant harmonic generation, a ripple is applied to both the cluster density and the surrounding plasma electron density. Using perturbation theory, the nonlinear current responsible for THG is analyzed. Numerical computations are performed to explore the impact of various laser and cluster parameters on the efficiency of the generated third harmonics. Additionally, it is observed that the anharmonic cluster structures exhibit strong optical nonlinearities, broadening the surface plasmon resonance.