Squeezing Photons into a Point-Like Space

Myung-Ki Kim, Hongchul Sim, Seung Ju Yoon, Su-Hyun Gong, Chi Won Ahn, Yong Hoon Cho, Yong Hee Lee

Research output: Contribution to journalArticle

49 Citations (Scopus)


Confining photons in the smallest possible volume has long been an objective of the nanophotonics community. In this Letter, we propose and demonstrate a three-dimensional (3D) gap-plasmon antenna that enables extreme photon squeezing in a 3D fashion with a modal volume of 1.3 × 10-7 λ3 (∼4 × 10 × 10 nm3) and an intensity enhancement of 400 000. A three-dimensionally tapered 4 nm air-gap is formed at the center of a complementary nanodiabolo structure by ion-milling 100 nm-thick gold film along all three dimensions using proximal milling techniques. From a 4 nm-gap antenna, a nonlinear second-harmonic signal more than 27 000-times stronger than that from a 100 nm-gap antenna is observed. In addition, scanning cathodoluminescence images confirm unambiguous photon confinement in a resolution-limited area 20 × 20 nm2 on top of the nano gap. (Figure Presented).

Original languageEnglish
Pages (from-to)4102-4107
Number of pages6
JournalNano Letters
Issue number6
Publication statusPublished - 2015 Jun 10
Externally publishedYes


  • 3D gap-plasmon antennas
  • 3D nanofabrications
  • nano-optics
  • Plasmonics

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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  • Cite this

    Kim, M-K., Sim, H., Yoon, S. J., Gong, S-H., Ahn, C. W., Cho, Y. H., & Lee, Y. H. (2015). Squeezing Photons into a Point-Like Space. Nano Letters, 15(6), 4102-4107. https://doi.org/10.1021/acs.nanolett.5b01204