Anti-Parallel Dipole Coupling of Quantum Dots via an Optical Near-Field Interaction

Tadashi KAWAZOE  Kiyoshi KOBAYASHI  Motoichi OHTSU 

Publication
IEICE TRANSACTIONS on Electronics  Vol.E88-C  No.9  pp.1845-1849
Publication Date: 2005/09/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Nanophotonics and Related Techniques)
Category: 
Keyword: 
optical near-field interaction,  anti-parallel electric dipole pair,  near-field spectroscopy,  coupled quantum dots, 

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Summary: 
We observed the optically forbidden energy transfer between cubic CuCl quantum dots coupled via an optical near-field interaction using time-resolved near-field photoluminescence (PL) spectroscopy. The energy transfer time and exciton lifetime were estimated from the rise and decay times of the PL pump-probe signal, respectively. We found that the exciton lifetime increased as the energy transfer time fell. This result strongly supports the notion that near-field interaction between QD makes the anti-parallel dipole coupling. Namely, a quantum-dots pair coupled by an optical near field has a long exciton lifetime which indicates the anti-parallel coupling of QDs forming a weakly radiative quadrupole state.