Terahertz whispering gallery mode bubble resonator

TL;DR

This paper demonstrates the existence of whispering gallery modes in terahertz quartz bubble resonators, achieving high Q-factors and revealing their potential for sensitive THz sensing applications.

Contribution

It presents the first detailed study of THz WGMs in quartz bubble resonators, including amplitude and phase analysis, with experimental results matching models and simulations.

Findings

High Q-factor exceeding 440 at 0.47 THz

Excellent agreement between measurements, models, and simulations

Potential for highly sensitive THz sensors

Abstract

Whispering gallery mode (WGM) resonators are compelling optical devices, however they are nearly unexplored in the terahertz (THz) domain. In this letter, we report on THz WGMs in quartz glass bubble resonators with sub-wavelength wall thickness. An unprecedented study of both the amplitude and phase of THz WGMs is presented. The coherent THz frequency domain measurements are in excellent agreement with a simple analytical model and results from numerical simulations. A high finesse of 9 and a quality (Q) factor exceeding 440 at 0.47 THz are observed. Due to the large evanescent field the high Q-factor THz WGM bubble resonators can be used as a compact, highly sensitive sensor in the intriguing THz frequency range.