Gallium arsenide whispering gallery mode resonators for terahertz photonics

TL;DR

This paper introduces a monolithic gallium arsenide whispering gallery mode resonator operating at terahertz frequencies, demonstrating its potential for nonlinear optics, tunability, and integration into THz photonic systems.

Contribution

It presents the fabrication and characterization of GaAs microdisk resonators with high Q-factors and demonstrates mode tuning via metal blocking, advancing THz nonlinear photonics.

Findings

Achieved Q-factors of 2.2k at 150 GHz and 1.4k at 300 GHz.

Demonstrated mode blue-shifting of up to 0.3 GHz using metal blocking.

Showcased potential for phase-matching and nonlinear THz applications.

Abstract

As the field of terahertz (THz) photonics advances, we present a monolithic gallium arsenide (GaAs) disk-shaped whispering gallery mode resonator that has potential as a component in THz nonlinear optics. GaAs is a material with significant optical nonlinearity which can be enhanced when the crystal is shaped into a microdisk resonator. A 4-mm-disk-resonator was fabricated using single-point diamond turning and was characterised to obtain a quality (Q) factor of 2.2k at ~150 GHz and 1.4k at ~300 GHz. We also demonstrated the blue-shifting of up to ~0.3 GHz of the THz modes using a block of metal. This post-fabrication degree of freedom could be useful for phase-matching requirements for nonlinear optical processes, such as detection based on optical up-conversion of THz radiation. Such a compact, tunable and efficient device could be integrated into nonlinear photonic platforms for THz generation, manipulation and detection.