Few optical-cycle pulse interactions with plasmas: models and nonlinear effects

We present an analysis of nonlinear optical effects when a high intense ultrashort laser pulse comprising only few field cycles propagates through an ionized medium. We introduce a model for the optical pulse and plasma based on the real electric field representation and the quantum mechanical description of electron dynamics in the ionization process. In the first part, we study the nonlinear atom response to such short driving pulses and the accompanied process of attosecond continuum production. In the second part, we analyze some collective plasma phenomena with ultrashort driving pulses, for which transverse effects are important. Among them, the processes of leaking mode self-channeling at saturable ionization, induced ionization scattering and large blueshifting with pulse shortening to a single-optical-cycle burst are of particular interest. © 1998 American Institute of Physics.