title: Enhanced surface-plasmon resonance absorption in metal-dielectric-metal layered microspheres.
abstract: We present a theoretical study of the dispersion relation of surface-plasmon resonances of mesoscopic metal-dielectric-metal microspheres. By analyzing the solutions to Maxwell's equations, we obtain a simple geometric condition for which the system exhibits a band of surface-plasmon modes whose resonant frequencies are weakly dependent on the multipole number. Using a modified Mie calculation, we find that a large number of modes belonging to this flat-dispersion band can be excited simultaneously by a plane wave, thus enhancing the absorption cross section. We demonstrate that the enhanced absorption peak of the sphere is geometrically tunable over the entire visible range.
authors.affiliation: Department of Physics, University of Oregon, 1371 East Thirteenth Avenue, Eugene, Oregon 97403, USA.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Charles
authors.initials: C
authors.lastname: Rohde
authors.forename: Miriam
authors.initials: M
authors.lastname: Deutsch