Analytical model for metal–insulator–metal mesh waveguide architectures

Metal–insulator–metal (MIM) waveguide mesh structures utilize X-junctions as power distribution elements to create interference and feedback effects, thereby providing rich device functionality. We present a generalized analytical model for MIM mesh structures by incorporating a modified characteristic impedance model for MIM junctions into the scatteringmatrix formalism. Themodified impedancemodel accounts for metal absorption and provides accurate prediction of plasmonic field distribution at X-junctions in terms of both magnitude and phase. Closed-form expressions for 2 × 1 and 2 × 2MIMmesh architectures as well as MIM stub structures are then obtained and are dependent only on waveguide geometry and junction configuration. The model does not require numerically extracted parameters, and results agree, within a few percent, with those obtained from finitedifference time-domain method for both two-dimensional and three-dimensional waveguide geometries. The capability of the model for efficient design and optimization of junction-based MIM devices is demonstrated through the development of various filter and resonant devices. © 2012 Optical Society of America OCIS codes: 000.4430, 350.4238, 250.5403, 240.6680, 240.6690, 050.6624.