QED effects in a cavity with a time-dependent thin semiconductor slab excited by laser pulses

We consider the problem of the creation of quanta of an electromagnetic field from the initial vacuum ( or thermal) state in a closed high-Q cavity due to periodical variations of conductivity of a thin semiconductor boundary layer excited by short laser pulses. Fast changes of conductivity from practically a zero value to a high one and then again to zero simulate periodical displacements of the cavity wall. This scheme has been chosen to model the non-stationary Casimir effect in the experiment which is under preparation at Padua University. We provide analytical and numerical evaluations for the number of photons which could be created under realistic experimental conditions. We show the importance of taking into account intrinsic losses in the semiconductor slab caused by the finite conductivity during the intermediate part of the excitation recombination cycle. We analyse the influence of different parameters, such as the diffusion and mobility coefficients of carriers, surface recombination velocity, absorption coefficient of laser radiation, thickness of the slab and geometry of the cavity. We conclude that a significant amount (> 103) of 'Casimir photons' with a frequency of 2.5 GHz can be produced from vacuum in a cavity with dimensions of the order of 10 cm, if one can arrange several thousand strongly periodical laser pulses with a duration of the order of 1 ps, periodicity close to 200 ps and energy similar to 10(-3) J, illuminating the semiconductor slab of thickness similar to 1 mm and the mobility similar to 1 m(2) V-1 s(-1), provided the recombination time can be reduced below the critical value similar to 30 ps.