Gallium arsenide whispering gallery mode resonators for terahertz photonics

25 September 2023·
Mallika Suresh
Mallika Suresh
Harald G. L. Schwefel
Harald G. L. Schwefel
,
Dominik Walter Vogt
· 0 min read
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 characterized to obtain a quality (Q) factor of 2.21k at ∼150 GHz and 1.41k 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. This proof-of-concept demonstration can pave the way for the implementation of a compact, tunable and efficient device which could be integrated into nonlinear photonic platforms for THz generation, manipulation and detection.
Type
Publication
Optics Express, 31(20), 33056-33063
Status
Peer-reviewed
publications
Photonics
Mallika Suresh
Authors
Mallika Suresh
Lead, Photonics
Mallika Suresh (Mika) is a Research Fellow at the Physics Department of the University of Otago and the Photonics Lead of Tuwhiri. For the last 5 years, her research has been focused on electro-optic nonlinear mixing of terahertz signals with optical modes in whispering gallery mode resonators. Before that, during her PhD, Mika worked with femtosecond pulses in gas-filled hollow-core fibres under the supervision of Prof. Philip Russell and Dr. Francesco Tani at the Max Planck Institute for the Science of Light. Soon after joining Harald’s team, she supervised the setting up of a femtosecond laser ablation system at the Physics Department for (among other applications) the fabrication of dielectric whispering gallery mode resonators for nonlinear optical experiments. She was the Agnes-Blackie Research Fellow of Te Whai Ao – Dodd-Walls Centre for Photonic and Quantum Technologies in 2024 – 2026 and now is an Associate Investigator in Te Whai Ao. Mika is also leading collaborations with international experts in the field of terahertz photonics such as Prof. Withawat Withayachumnankul at the University of Adelaide and Prof. Ileana-Cristina Benea-Chelmus at École Polytechnique Fédérale de Lausanne as part of the Tuwhiri programme.
Harald G. L. Schwefel
Authors
Harald G. L. Schwefel
Programme Leader / Principal Investigator

Harald Schwefel is a Professor in the Physics Department of the University of Otago and Science Lead of Tuwhiri. He is also the Deputy Director Science in Te Whai Ao – Dodd-Walls Centre for Photonic and Quantum Technologies and Principal Investigator in Quantum Technologies Aotearoa (QTA).

His research interests are in the use of optical resonators. Such high-quality resonators are great to generate very high field intensities. With high fields the interaction of light with matter can show significant nonlinearities and light can interact with itself and new colours can be created. A side effect of these high-quality resonators is that they are extremely sensitive to changes in the environment making them an ideal candidate to measure such changes.