Harmonic emission from cluster nanoplasmas subject to intense short laser pulses

TL;DR

This paper investigates harmonic emission from cluster nanoplasmas under intense laser pulses, revealing that nonlinear resonance-induced stochasticity suppresses high-order harmonic generation, supported by analytical modeling and previous simulation results.

Contribution

It provides an analytical model explaining the suppression of high-order harmonics due to nonlinear resonance effects in cluster nanoplasmas.

Findings

Resonant enhancement of low-order harmonics observed

High-order harmonics are suppressed at high intensities

Nonlinear resonance causes stochasticity that inhibits high-order harmonic emission

Abstract

Harmonic emission from cluster nanoplasmas subject to short intense infrared laser pulses is studied. In a previous publication [M. Kundu et al., Phys. Rev. A 76, 033201 (2007)] we reported particle-in-cell simulation results showing resonant enhancements of low-order harmonics when the Mie plasma frequency of the ionizing and expanding cluster resonates with the respective harmonic frequency. Simultaneously we found that high-order harmonics were barely present in the spectrum, even at high intensities. The current paper is focused on the analytical modeling of the process. We show that dynamical stochasticity owing to nonlinear resonance inhibits the emission of high order harmonics.