Directional emission from single nanocrystal quantum dots in Subwavelength metallic nanoslit arrays


  Nitzan Livneh [1]  ,  Ilai Schwarz [2]  ,  Itamar Rosenberg [2]  ,  Ayelet Strauss [1]  ,  Yossi Paltiel [1]  ,  Adiel Zimran [3]  ,  Uri Banin [3]  ,  Ronen Rapaport [1,2]  
[1] The Department of Applied Physics, The Hebrew University of Jerusalem
[2] Racah Institute of Physics, The Hebrew University of Jerusalem
[3] The Institute of Chamistry, The Hebrew University of Jerusalem

We demonstrate a directional beaming of the photons that are emitted from nanocrystal quantum dots embedded in a metallic nanoslit array, with a divergence angle of less than 4 degrees. We show that the eigenmodes of the structure result in localized electromagnetic field enhancements at the extraordinary transmission (EOT) Bragg cavity resonances, which could be controlled and engineered in both real and momentum space.  The photon beaming is achieved using the resonant coupling of the quantum dots to the Bragg standing EOT modes, where exciton-plasmon polariton coupling dominates the emission properties of the quantum dots. We show this beaming effect down to the single quantum dot – single photon level. Therefore we conclude that engineering nanocrystal quantum dots with subwavelength metallic nanostructures is a promising way for a range of new types of active optical devices down to single photon levels, where spatial and temporal control of the optical properties of nano-emitters is essential.