Interference spectra transformation of counter-propagating pulses propagating through a dielectric slab

A phenomenon of spectra transformation of counter-propagating electromagnetic pulses which propagate through a dielectric slab is studied. The spectra transformation occurs due to the interference energy flux which exists during the propagation of pulses through a slab. The physical conditions (time matching, amplitude matching and existence of the slab critical size) under which the maximal interference energy flux is observed are discussed. It is found that the interference energy flux modulates the spectra of the initial signals and transfers energy through the slab unequally at different frequencies. The energy transfer does not occur at multiple frequencies which correspond to the reflectionless passage of monochromatic waves through the slab.