21 - Layered photonic crystals with left-handed materials

Abstract

We theoretically investigate the photonic band structure of layered photonic crystals composed of alternating layers of right- and left-handed materials (RHMs and LHMs). The dispersion curves are mainly studied by assuming that the dielectric permittivity and magnetic permeability are constant in each layer. It is shown that such structures can exhibit new types of electromagnetic modes and dispersion curves that do not exist in usual photonic crystals composed only of RHMs. In particular, we emphasize the possibility of bands that originate from the interface modes localized at the boundary between an LHM and RHM or from confined modes in one type of layers. These waves are evanescent in both or in one constituent of the photonic crystal. One of the passbands may lie below the light lines of the constituting material and go down to the static limit of a vanishing frequency ω, even at a value of the wavevector k|| (parallel to the layers) that is different from zero. For a given value of the wavevector k||, the dispersion curves ω versus k3 (where k3 is the Bloch wavevector of the periodic system along the axis of the photonic crystal) may exist only in a limited part of the photonic crystal Brillouin zone and exhibit a zigzag behavior instead of a monotonic behavior as in usual photonic crystals. With an appropriate choice of the parameters, we show that it is possible to realize an absolute (or omnidirectional) bandgap for either transverse electric (TE) or transverse magnetic (TM) polarization of the electromagnetic waves. A combination of two multilayer structures composed of RHMs and LHMs is proposed to realize, in a certain range of frequency, an omnidirectional reflector of light for both polarizations.