FREQUENCY-SHIFTING OF ELECTROMAGNETIC-RADIATION BY SUDDEN CREATION OF A PLASMA SLAB

The effect of switching a plasma medium of finite width (slab) on a time-harmonic plane electromagnetic wave propagating in free space is considered. The transient solution is obtained through the use of Laplace transforms. The solution is broken into two components: A component which in steady state has the same frequency as the incident wave frequency (omega0) and a B component which has an upshifted frequency omega1 = square-root omega0(2) + omega(p)2. Here omega(p) is the plasma frequency of the switched plasma slab. Numerical results are presented to show the effect of the slab width on the reflected and transmitted waves. A proper choice of omega0, omega(p) and the slab width will yield a transmitted electromagnetic pulse of significant strength at the upshifted frequency.