Directional Emission of Dielectric Disks with a Finite Scatterer in the THz Regime

TL;DR

This paper explores how small scatterers near dielectric disks in the THz range can induce directional emission in whispering gallery mode resonators, maintaining high quality factors, with potential applications in lasers and sensors.

Contribution

It demonstrates that small perturbations can enable directional emission without degrading the resonator's quality factor, supported by both numerical simulations and experimental validation.

Findings

Scatterers enable directional emission in THz whispering gallery resonators.

Quality factor remains high despite perturbation.

Experimental results align with simulations.

Abstract

In the Terahertz (THz) domain, we investigate both numerically and experimentally the directional emission of whispering gallery mode resonators that are perturbed by a small scatterer in the vicinity of the resonators rim. We determine quality factor degradation, the modal structure and the emission direction for various geometries. We find that scatterers do allow for directional emission without destroying the resonator's quality factor. This finding allows for new geometries and outcoupling scenarios for active whispering gallery mode structures such as quantum cascade lasers and passive resonators such as evanescent sensors. The experimental results agree well with finite difference time domain simulations.