Unidirectional Spaser in Symmetry-Broken Plasmonic Core-Shell Nanocavity

作者：Meng Xiangeng^*; Guler Urcan; Kildishev Alexander V; Fujita Koji; Tanaka Katsuhisa; Shalaev Vladimir M

来源：Scientific Reports, 2013, 3(1): 1241.

DOI：10.1038/srep01241

The spaser, a quantum amplifier of surface plasmons by stimulated emission of radiation, is recognized as a coherent light source capable of confining optical fields at subwavelength scale. The control over the directionality of spasing has not been addressed so far, especially for a single-particle spasing nanocavity where optical feedback is solely provided by a plasmon resonance. In this work we numerically examine an asymmetric spaser - a resonant system comprising a dielectric core capped by a metal semishell. The proposed spaser emits unidirectionally along the axis of the semishell; this directionality depends neither on the incident polarization nor on the incident angle of the pump. The spasing efficiency of the semishell-capped resonator is one order of magnitude higher than that in the closed core-shell counterpart. Our calculations indicate that symmetry breaking can serve as a route to create unidirectional, highly intense, single-particle, coherent light sources at subwavelength scale.

• 出版日期2013-2-7