title: An ultra-short contra-directional coupler utilizing surface plasmon-polaritons at optical frequencies.
abstract: A nano-scaled coupled-line coupler based on the guidance of surface plasmon-polaritons (SPPs) is proposed, designed and simulated at optical frequencies. The coupler comprises layered dielectric materials and silver, which serve as two stacked nano-transmission lines to achieve broadside coupling. The key property of this coupler is that it operates based on the principle of contra-directional coupling between a forward and a backward wave giving rise to supermodes that are characterized by complex-conjugate eigenvalues (even when the materials are assumed lossless). The resulting exponential attenuation along the coupler leads to dramatically reduced coupling lengths compared to previously reported co-directional SPP couplers (e.g. from millimeters to submicrons). The effect of material losses and finite coupler width are also analyzed.
authors.affiliation: The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON, Canada.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Rubaiyat
authors.initials: R
authors.lastname: Islam
authors.forename: George V
authors.initials: GV
authors.lastname: Eleftheriades
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003198:Computer Simulation; D004867:Equipment Design; D008962:Models, Theoretical; D055095:Optics and Photonics / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*