Time-domain observation of strong coupling between counter-propagating ultra-high Q whispering gallery modes

Wataru Yoshiki, Akitoshi Chen-Jinnai, Tomohiro Tetsumoto, Shun Fujii, Takasumi Tanabe

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)


An ultra-high Q whispering gallery mode (WGM) cavity is attractive because the light-matter interaction is enhanced inside it. In terms of science and engineering, an interesting use of a WGM cavity is as a coupled system. When two cavity modes are strongly coupled, they are split in the frequency domain and photons are transferred cyclically between the two modes in the time domain. Recently, the time-domain observation and control of the coupling states were reported with photonic crystal nanocavities, and this technology is essential for developing a quantum node and a quantum network. However, such experiments have not yet been achieved with ultra-high Q modes despite the potential benefit to be gained from the use of ultra-high Q cavities. In this study, we observed strong coupling between ultra-high Q modes in the time domain for the first time. We employed two counter-propagating modes that coupled with each other via surface scattering in a silica toroid microcavity. We employed two tapered fibers (add-drop configuration), one for excitation and the other for observing the energy oscillation between two cavities, which is a necessary technique for directly observing energy in a cavity. The results revealed clear oscillatory behavior, which was induced by the strong coupling. In addition, the oscillation period in the time domain precisely matched that inferred from the mode splitting in the frequency domain, and the measured results showed excellent agreement with those calculated with the developed numerical model.

Original languageEnglish
Title of host publicationLaser Resonators, Microresonators, and Beam Control XVIII
EditorsAlexis V. Kudryashov, Alan H. Paxton, Vladimir S. Ilchenko, Lutz Aschke
ISBN (Electronic)9781628419627
Publication statusPublished - 2016
EventLaser Resonators, Microresonators, and Beam Control XVIII - San Francisco, United States
Duration: 2016 Feb 152016 Feb 18

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherLaser Resonators, Microresonators, and Beam Control XVIII
Country/TerritoryUnited States
CitySan Francisco


  • Coupled resonator
  • Microcavity
  • Rabi oscillation
  • Rabi splitting

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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