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Tunable terahertz source on a chip with decade-long stability using layered-superconductor elliptical microcavities

Mingqi Zhang1, Shungo Nakagawa2, Yuki Enomoto2, Yoshihiko Kuzumi2, Ryuta Kikuchi2, Yuki Yamauchi2, Toshiaki Hattori3, Richard A. Klemm4, Kazuo Kadowaki2 et al.

Takanari Kashiwagi2 and Kaveh Delfanazari1,*

  • 1James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
  • 2Department of Materials Science, Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tenoudai, Tsukuba, Ibaraki 305-8573, Japan
  • 3Department of Applied Physics, Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tenoudai, Tsukuba, Ibaraki 305-8573, Japan
  • 4Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, Florida 32816-2385, USA

  • *Contact author: Kaveh.Delfanazari@glasgow.ac.uk
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Phys. Rev. Applied 24, 054012 – Published 5 November, 2025

DOI: https://doi.org/10.1103/pwlx-4sjf

Abstract

Chip-scale, electrically tunable, continuous-wave, coherent terahertz (THz) radiation sources are critical for emerging applications in sensing, imaging, spectroscopy, communications, space, and quantum technologies. Here, we demonstrate a robust source-on-a-chip THz emitter based on a layered high-temperature superconductor, engineered with an elliptical microcavity and capable of sustained coherent emission over an unprecedented operational lifetime exceeding 11 years. This compact THz source operates up to 60 K (with Tc ≈ 90 K), delivering stable radiation in the 0.7–0.8 THz range, with on-chip electrical tunability from 100 GHz to 1 THz. Coherence arises from the phase-locked oscillation of intrinsic Josephson junction arrays, resonantly coupled to transverse electromagnetic modes within the cavity, analogous to a laser cavity, yielding collective macroscopic oscillations. THz emission remains detectable across an approximately 0.5-m free-space open-air link at room temperature. We analyse the cavity-mode structure and extract THz photon generation rates up to approximately 503 photons fs−1 in cryogenic conditions and 50–260 photons ps−1 over the air. These results demonstrate, for the first time, sustained and electrically tunable coherent THz emission from superconductors over multiyear timescales, defining another class of robust, chip-integrated THz lasers with applications in scalable THz and quantum technologies.

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Phys. Rev. Applied 24, 054012– Published 5 November, 2025
  • Received 29 March 2025
  • Revised 24 August 2025
  • Accepted 24 September 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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