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.
© 2006 Optical Society of America
Original Manuscript: November 29, 2005
Revised Manuscript: January 18, 2006
Manuscript Accepted: January 20, 2006
Vol. 1, Iss. 5 Virtual Journal for Biomedical Optics
Keisuke Hasegawa, Charles Rohde, and Miriam Deutsch, "Enhanced surface-plasmon resonance absorption in metal-dielectric-metal layered microspheres," Opt. Lett. 31, 1136-1138 (2006)