Unidirectional enhanced spontaneous emission with metallo-dielectric optical antenna

metallo-dielectric system consisted of two coupled metallic nanoparticles embedded in a planar dielectric antenna is proposed to control the light emission from a localized emitter. Such design integrates the advantages of planar dielectric antenna and plasmonic antenna such as highly localized excitation enhancement, emission direction control, and high collection efficiency. For specific configurations, the antenna can achieve unidirectional and plasmon-enhanced emission from single emitters, simultaneously presenting remarkable collection efficiency up to 96%. We show that the unidirectional effect is mainly determined by the plasmon coupling effect of the plasmonic dimer. The dependences of directivity property on the antenna geometry and emitter's position are also discussed in detail. These findings provide a promising route to realize novel optical devices involving directional and surface enhanced spontaneous emission, e.g. bright single-photon sources with high collection efficiency. (C) 2015 Elsevier B.V. All rights reserved.National Key Basic Research Program of China [2013CB328703]; National Natural Science Foundation of China [61422502, 11374026, 91221304, 61521004]SCI(E)ARTICLE,SI133-13839