Surface modes in left-handed material slab waveguides

摘要

We present a detailed study of surface guided modes in slab waveguides with a left-handed material (LHM) core sandwiched between a right-handed cover and a right-handed substrate. Universal dispersion curves and dispersion properties are obtained analytically. It is found that the guidance properties differ remarkably for different LHM constitutive parameters. Depending on these different constitutive parameters and their relations, we consider the following three cases: (I) the absolute permeability values of both cladding layers are less than that of the core; (II) only one cladding layer has absolute permeability value less than the core; and (III) neither cladding layer has absolute permeability less than the core. The surface TE1 mode always exists in all three cases. Its dispersion curve smoothly connects with that of the oscillating TE1 mode to form a whole mode. In case I, such a whole mode exists for a very small slab thickness. In cases II and III, the whole mode behaves in the same way as other higher-order oscillating modes. The surface TE0 mode exists only in case III without cut-off and it has abnormal dispersion. A physical explanation for the propagation of guided surface modes in LHM slab waveguides is given. Both TE and TM surface guided modes are discussed.