Surface acoustic wave (SAW) resonators can confine and enhance the displacement associated with SAW phonons. SAW resonators are useful in quantum technology, where they are used to enhance the...Show moreSurface acoustic wave (SAW) resonators can confine and enhance the displacement associated with SAW phonons. SAW resonators are useful in quantum technology, where they are used to enhance the coupling between a single phonon and a semiconductor quantum dot (QD). In this thesis, the fabrication process of SAW resonators on GaAs with acoustic mirrors based on aluminum Bragg reflectors, and an investigation into the relation between the finesse of a resonator and the thickness of the aluminum mirrors are detailed. For this purpose, three resonators identical in design apart from the thickness of their aluminum mirrors (35 nm, 50 nm, and 100 nm) are fabricated. The finesse of these resonators is derived by examining their acoustic resonance spectra and displacement maps. Both types of measurements are performed with a fiber-based scanning Michelson interferometer. It is found that losses associated with the resonator limit the finesse. The maximal finesse is found to be F ≈ 11 for the 100 nm resonator. Based on the measurement results, it is hypothesized that reducing the resonator length will lead to a decrease in propagation loss, thereby raising the upper limit of the finesse. This project has been a step towards the optical detection of thermal phonons, with its final goal to detect single phonons.Show less
In this research project, we attempt to develop numerical simulation models to investigate surface acoustic waves (SAWs) and how they can be efficiently excited using interdigital transducers (IDTs...Show moreIn this research project, we attempt to develop numerical simulation models to investigate surface acoustic waves (SAWs) and how they can be efficiently excited using interdigital transducers (IDTs). These devices already find use in applications such as filtering devices for mobile communication systems. We identified the equation of motion in solids, Gauss’ law of electrostatics and the piezoelectric constitutive equations combined with material properties as the basic physics required to model IDTs. Based on these equations, we developed 2D and 3D finite element method (FEM) simulations in COMSOL, with lithium niobate and gallium arsenide as substrate materials, which we used to investigate the IDT frequency response. We also investigated the transient response of IDTs. Our results are in good agreement with analytic theory, which validates our model and approach. These models can now be used to optimize IDT device designs. Lastly, we propose and implement the first steps toward an optical setup based on a Michelson interferometer to detect surface acoustic waves.Show less
