Abstract

The vast majority of resonant systems show a red-shift for the resonance frequency when a perturbation, e.g., losses, is introduced to the system. In contrast, here we report for the first time, to the best of our knowledge, the experimental demonstration of both red- and anomalous blue-shifting of whispering-gallery modes (WGMs) using dielectric and metallic substrates. The maximum blue-shift is more than three times as large as the expected red-shift, proving that the anomalous blue-shift is more than a peculiar curiosity. The experiments are performed in the terahertz frequency range with coherent continuous-wave spectroscopy. The results establish dielectric and metallic tuning as a novel and viable approach to tune high-quality WGMs and provide valuable insights into the anomalous blue-shift of WGM cavity systems. The tuning capabilities for these compact monolithic resonators are of significant interest for fundamental science and technological applications alike.

© 2019 Optical Society of America

On-chip single-mode high-Q terahertz whispering gallery mode resonator

Ziwei Wang, Shixing Yuan, Gaoneng Dong, Ruolan Wang, Liao Chen, Xiaojun Wu, and Xinliang Zhang
Opt. Lett. 44(11) 2835-2838 (2019)

Free-space coupling to symmetric high-Q terahertz whispering-gallery mode resonators

Dominik Walter Vogt, Angus Harvey Jones, and Rainer Leonhardt
Opt. Lett. 44(9) 2220-2223 (2019)

Voltage-actuated thermally tunable on-chip terahertz filters based on a whispering gallery mode resonator

Ziwei Wang, Gaoneng Dong, Shixing Yuan, Liao Chen, Xiaojun Wu, and Xinliang Zhang
Opt. Lett. 44(19) 4670-4673 (2019)

Mode coupling in a terahertz multi-mode whispering-gallery-mode resonator

Shixing Yuan, Liao Chen, Ziwei Wang, Ruolan Wang, Xiaojun Wu, and Xinliang Zhang
Opt. Lett. 44(8) 2020-2023 (2019)

Dielectric tuning and coupling of whispering gallery modes using an anisotropic prism

Matthew R. Foreman, Florian Sedlmeir, Harald G. L. Schwefel, and Gerd Leuchs
J. Opt. Soc. Am. B 33(11) 2177-2195 (2016)