Parametric excitation of vacuum by use of femtosecond laser pulses

We discuss the method of parametric excitation of electromagnetic waves in a cavity by creation of a dense plasma layer (which represents the 'mobile' wall of the cavity) due to irradiation of semiconductor film with femtosecond laser pulse. The effect is analyzed for the various initial states including the initial vacuum state. The state of the field produced by this method from initial vacuum state differs from electromagnetic field of another origin because only even quantum levels are populated (similar to Shrodinger cat states) and specific distribution of wave packet in phase space takes place. Besides parametrically excited field has specific angle distribution and appears in shorter time scales than ones required for appearance of radiation of another origin. The instantaneous and adiabatic slow excitation of eigenmodes of the cavity are described. The estimations for experimental detection of the effect are made.