Noninvasive Near‐Field Spectroscopy of Single Subwavelength Complementary Resonators

Journal Article · Thu Mar 05 00:00:00 EST 2020 · Laser & Photonics Reviews

DOI:https://doi.org/10.1002/lpor.201900254· OSTI ID:1603381

Hale, Lucy L. ^[1]; Keller, Janine  ^[2]; Siday, Thomas  ^[1]; Hermans, Rodolfo I.  ^[1]; Haase, Johannes ^[3]; Reno, John L. ^[4]; Brener, Igal ^[4]; Scalari, Giacomo  ^[2]; Faist, Jérôme ^[2]; Mitrofanov, Oleg  ^[5]

---

1. Electronic and Electrical Engineering University College London London WC1E 7JE UK
2. Institute of Quantum Electronics ETH Zürich Zürich 8093 Switzerland
3. Paul Scherrer Institute Villigen 5232 Switzerland
4. Sandia National Laboratories Albuquerque NM 87185 USA
5. Electronic and Electrical Engineering University College London London WC1E 7JE UK, Sandia National Laboratories Albuquerque NM 87185 USA

Abstract Subwavelength metallic resonators provide a route to achieving strong light–matter coupling by means of tight confinement of resonant electromagnetic fields. Investigation of such resonators however often presents experimental difficulties, particularly at terahertz (THz) frequencies. A single subwavelength resonator interacts weakly with THz beams, making it difficult to probe it using far‐field methods, whereas arrays of resonators exhibit inter‐resonator coupling, which affect the resonator spectral signature and field confinement. Here, traditional far‐field THz spectroscopy is systematically compared with aperture‐type THz near‐field microscopy for investigating complementary THz resonators. While the far‐field method proves impractical for measuring single resonators, the near‐field technique gives high signal‐to‐noise spectral information, only achievable in the far‐field with resonator arrays. At the same time, the near‐field technique allows to analyze single resonators without significant interaction with the near‐field probe. Furthermore, the near‐field technique allows highly confined fields and surface waves to be mapped in space and time. This information gives invaluable insight into spectral response in resonator arrays. This near‐field microscopy and spectroscopy method enables investigations of strong light–matter coupling at THz frequencies in the single‐resonator regime.

• Sponsoring Organization: USDOE
• OSTI ID: 1603381
• Journal Information: Laser & Photonics Reviews, Journal Name: Laser & Photonics Reviews Vol. 14 Journal Issue: 4; ISSN 1863-8880
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English