English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

An exact infinite set of coupled ordinary differential equations, describingthe evolution of the modes of the classical electromagnetic field inside anideal cavity, containing a thin slab with the time-dependent conductivity$\sigma(t)$ and dielectric permittivity $\varepsilon(t)$, is derived for thedispersion-less media. This problem is analyzed in connection with the attemptsto simulate the so called Dynamical Casimir Effect in three-dimensionalelectromagnetic cavities, containing a thin semiconductor slab, periodicallyilluminated by strong laser pulses. Therefore it is assumed that functions$\sigma(t)$ and $\delta\varepsilon(t)=\varepsilon(t)-\varepsilon(0)$ aredifferent from zero during short time intervals (pulses) only. The main goal isto find the conditions, under which the initial nonzero classical field couldbe amplified after a single pulse (or a series of pulses). Approximatesolutions to the dynamical equations are obtained in the cases of "small" and"big" maximal values of the functions $\sigma(t)$ and $\delta\varepsilon(t)$.  It is shown, that the single-mode approximation, used in the previousstudies, can be justified in the case of "small" perturbations. But theinitially excited field mode cannot be amplified in this case, if the laserpulses generate free carriers inside the slab. The amplification could bepossible, in principle, for extremely high maximal values of conductivity andthe concentration of free carries (the model of "almost ideal conductor"),created inside the slab, under the crucial condition, that the function$\delta\varepsilon(t)$ is {\em negative}. This result follows from a simpleapproximate analytical solution, and it is confirmed by exact numericalcalculations. However, the evaluations show, that the necessary energy of laserpulses must be, probably, unrealistically high.

Excitation of the classical electromagnetic field in a cavity containing a thin slab with a time-dependent conductivity