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Revision with unchanged content. In this thesis, the first detailed investigations have been made on three-halves harmonic radiation generated in femtosecond-laser-produced plasmas. Several important properties of the parametric instabilities stimulated Raman scattering (SRS) and two-plasmon decay (TPD) in this regime have been deduced from the results with the help of theoretical models. In the interaction of ultrahigh intensity Titanium:sapphire femtosecond laser with solid targets, a strong green light emission is regularly observed. This radiation is generally attributed to collective plasma effects and in particular to an emission at three-halves harmonic of the fundamental frequency (3 0/2), which has previously been investigated only with nanosecond lasers. The purpose of this work is to systematically study the 3 0/2 emission from femtosecond-laser-produced plasmas, with the ultimate aim of identifying possible applications of this radiation source. To this end, the work has been organised into 3 parts, each broadly representing a separate experimental campaign.

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Laszlo Veisz, received the M.S. degree in physics from the Eötvös Loránd University, Budapest, Hungary, and the Ph.D. degree from the Friedrich-Schiller-University, Jena, Germany in 2003. He is currently with the Max Planck Institute of Quantum Optics, Garching, Germany, working on laser-driven electron acceleration and OPCPA system development.

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