Near-field optical spectroscopy of excitons in single quantum dots

Toshiharu Saiki, Kenichi Nishi

Research output: Contribution to journalConference articlepeer-review


InGaAs single quantum dot photoluminescence spectra and images are investigated by using a low-temperature near-field optical microscope. By modifying the commonly used near-field apertured probe, a high spatial resolution and high detection efficiency are achieved simultaneously. Local collection of the emission signal through a 500 nm (λ/2) aperture contributes to the single-dot imaging with a λ/6 resolution, which is a significant improvement over the conventional spatially resolved spectroscopy. Tailoring the tapered structure of the near-field probe enables us to obtain the emission spectra of single dots in the weak excitation region, where the carrier injection rate is ∼107 excitons/s per dot. By employing such a technique, we examine the evolution of single-dot emission spectra with excitation intensity. In addition to the ground-state emission, excited-state and biexciton emissions are observed for higher excitation intensities. By a precise investigation of the excitation power dependences of individual dots, two-dimensional identification of their emission origins is obtained for the first time.

Original languageEnglish
Pages (from-to)212-221
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 1998
Externally publishedYes
EventFar- and Near-Field Optics: Physics and Information Processing - San Diego, CA, United States
Duration: 1998 Jul 231998 Jul 24


  • Biexciton
  • Exciton
  • Near-field optical microscope
  • Photoluminescence
  • Quantum dot

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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