Enhanced surface-plasmon resonance absorption in metal-dielectric-metal layered microspheres.
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.
Hasegawa
Keisuke
K
Department of Physics, University of Oregon, 1371 East Thirteenth Avenue, Eugene, Oregon 97403, USA.
Rohde
Charles
C
Deutsch
Miriam
M