Directional radiation enhancement of nanowire quantum dots based on line-array plasmonic antenna coupling

Abstract

The integration of a single III-V semiconductor quantum dot with a plasmonic nanoantenna as a means toward efficient single-photon sources (SPEs) is limited due to its weak, wide-angle emission, and low emission rate. These limitations can be overcome by designing a unique linear array of plasmonic antenna structures coupled to nanowire-based quantum dot (NWQD) emitters. A linear array of a coupled device composed of multiple plasmonic antennas at an optimum distance from the quantum dot emitter can be designed to enhance the directionality and the spontaneous emission rate of an integrated single-photon emitter. Finite element modeling has been used to design these compact structures with high quantum efficiencies and directionality of single-photon emission while retaining the advantages of NWQDs. The Purcell enhancement factor of these structures approaches 66.1 and 145.8, respectively. Compared to a single NWQD of the same diameter, the fluorescence was enhanced by 1054 and 2916 times. The predicted collection efficiencies approach 85% (numerical aperture, NA = 0.5 ) and 80% ( NA = 0.5 ), respectively. Unlike single-photon emitters based on bulky conventional optics, this is a unique nanophotonic single-emission photon source based on a line-array configuration that uses a surface plasmon-enhanced design with minimum dissipation. The designs presented in this work will facilitate the development of SPEs with potential integration with semiconductor optoelectronics.