Integrated GaAs-on-insulator platform for quantum dot single-photon emitter

Single-photon sources stand out as one of the most critical components within integrated photonic quantum systems. III-V semiconductor quantum dot has been regarded as an excellent single-photon source for its deterministic, pure, and indistinguishable single-photon emission. The quest for optimal quantum dot single-photon sources has led to the exploration of various material platforms, including deep-etched GaAs/AlGaAs, suspended GaAs membranes, and hybrid material systems. This thesis presents a new integrated material platform for on-chip quantum information processing, GaAs-on-insulator (GaAsOI). It features high-index contrast, which enables the high coupling efficiency from the emitter to the waveguide. This thesis will investigate the potential of this platform for quantum dot single-photon sources. Central to our investigation is the Purcell effect, a pivotal tool for enhancing the brightness and single-photon properties of solid-state single-photon emitters. This thesis aims to enhance the Purcell effect through both theoretical simulations and experiment investigation. In simulations, we will explore enhancing the Purcell effect by confining light to a sub-wavelength dimension, leveraging the boundary conditions at material interfaces. Two different nanophotonic structures will be investigated: a V-groove waveguide and a circular Bragg grating cavity integrated with two air triangles, which exhibit a Purcell factor of ∼8 and ∼87, respectively. Although these proposed structures may not accommodate quantum dots, they hold potential for a broad array of atomic-scale solid-state single-photon sources, including color centers in diamonds, silicon, and silicon carbide. Experimentally, we will introduce the fabrication process of the GaAsOI material platform. Building upon the well-developed fabrication process, a series of cavity designs will be demonstrated on this platform. We will first show a microring cavity quantum dot single-photon source with a quality factor of around 9,000, which enables a moderate Purcell factor of 1.6. The device demonstrates the single-photon purity of 97% and two-photon interference visibility of 0.517. To further enhance the Purcell effect, we propose to employ a small mode volume cavity design, the nanobeam cavity and fishbone cavity, which are further examined on this platform. The nanobeam cavity shows a quality factor reaching ∼2,500. A particular device with a quality factor of ∼1,300 exhibited a Purcell factor of ∼9.5 and a multi-photon suppression of 0.295. The fishbone cavity design will be further introduced and demonstrate a quality factor of ∼2,400. Beyond single-photon emitters, the proposed GaAsOI material platform can also accommodate various optical components, including but not limited to quantum circuits, modulators, and single-photon detectors. This versatility can make this integrated platform a strong candidate for comprehensive integrated quantum information processing.