DIRAC POINTS, TOPOLOGICAL EDGE MODES AND NONRECIPROCAL TRANSMISSION IN ONE-DIMENSIONAL METAMATERIAL-BASED COUPLED-CAVITY ARRAYS

We show that topological frequency band structures emerge in one-dimensional (1D) electromagnetic (EM) lattices of metamaterial components without the application of an external magnetic field. Such lattices can be cavity arrays coupled with metamaterial elements which generate alternate positive and negative-phase hopping strengths. The topological nature of the band structure manifests itself by the occurrence of Dirac points in the band structure, by the emergence of edge modes in finite arrays as well as by a nonreciprocal scattering spectrum. Specific EM designs for demonstrating the above phenomena are discussed.