Three-halves harmonic emission from femtosecond laser produced plasmas (original) (raw)

Measurements of three-halves harmonic radiation (3/2) produced by femtosecond, Ti:sapphire laser pulses (2×10^17 W/cm^2) in long density scale length plasmas generated from solid aluminum targets are presented. The 3/2 emission yield shows excellent agreement with theories of the two-plasmon decay instability in the predominantly linear regime. High intensity femtosecond laser produced plasmas form the basis of important research topics such as x-ray lasers, laser driven particle accelerator schemes, and relativistic effects in laser-plasmas. This article reports first experimental studies of high intensity fs-laser generated 3/2 radiation in inhomogeneous plasmas and shows that measurements of the 3/2-harmonic yield as a function of the incident pulse duration are in excellent agreement with linear theories.