Gallium arsenide whispering gallery mode resonators for terahertz photonics

Area of Science:

• Photonics
• Optics
• Materials Science

Background:

• Terahertz (THz) photonics is a rapidly advancing field.
• Gallium arsenide (GaAs) possesses significant optical nonlinearity, enhanced in microdisk resonators.
• Whispering gallery mode resonators offer unique properties for optical applications.

Purpose of the Study:

• To present a monolithic GaAs disk-shaped whispering gallery mode resonator for THz nonlinear optics.
• To demonstrate the potential of this resonator as a component in THz nonlinear optical systems.
• To explore post-fabrication tuning for phase-matching requirements in nonlinear optical processes.

Main Methods:

• Fabrication of a 4-mm-disk-resonator using single-point diamond turning.
• Characterization of the resonator to determine its quality (Q) factor at different frequencies.
• Demonstration of THz mode blue-shifting using a metal block for post-fabrication tuning.

Main Results:

• Achieved a quality (Q) factor of 2.21k at ~150 GHz and 1.41k at ~300 GHz.
• Demonstrated a blue-shifting of THz modes by up to ~0.3 GHz.
• Validated the potential for tuning resonator modes for phase-matching.

Conclusions:

• The monolithic GaAs disk resonator is a promising component for THz nonlinear optics.
• Post-fabrication tuning offers a degree of freedom for optimizing nonlinear optical processes.
• This work paves the way for compact, tunable, and efficient THz devices for generation, manipulation, and detection.