Dual Representation of Field Evolution in Dielectric Waveguide with Time Discontinuity

It was shown long ago that time changing of the medium permittivity leads to change of an electromagnetic field (Morgenthaler, 1958). This changing occurs immediately in the unbounded medium if the permittivity changes sharply. In the presence of boundaries as in the case of a waveguide or a resonator this process is more complex because of dispersion in such a structure. Such processes in a dielectric waveguide and in a dielectric resonator have been considered in (Nerukh et al., 2004) and (Sakhnenko et al., 2005). Two representations of an electromagnetic wave evolution in a dielectric waveguide caused by changing its permittivity is analysed in this paper.