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We analyze the propagation of an incident electromagnetic wave in apurely-time modulated medium. Precisely, we assume that the permeability isunchanged while the permittivity has a multiple-step profile in time anduniformly constant in space. For this, we use time-dispersive Lorenz's modelwith time-dependent plasma frequency with highly concentrated values near thecenters of the steps' intervals. Under certain regimes linking the number ofsteps to the contrasts of the permittivity, we can generate effectivepermittivity having positive and high values on a finite interval of time whichbehaves as a 'wall' that kills the forward waves and keeps only the backwardwaves (i.e. enabling full reflection). But this happens if these high valuesare away from a discrete set. If these high values are close to the elements ofthis discrete set, then the effective medium behaves as a 'well' that absorbsall the forward waves and hence there is no backward waves (i.e. enabling fulltransmission). Such results are reminiscent to the 'wall' and 'well' effectsknown in the quantum mechanics theory.

Wave Propagation in Pure-Time Modulated Step Media With Applications to Temporal-Aiming