III-V Semiconductor Nano-Photonic Devices for Integrated Quantum Optical Circuits

The work presented in this thesis is motivated by the ultimate goal of realizing a fully integrated quantum optical circuit (IQOC), based on a III-V semiconductor, specifically gallium arsenide (GaAs), in a planar architecture with embedded indium arsenide (InAs) quantum dots as single photon sources. Technological challenges involved with achieving a scalable quantum photonic circuit are addressed through the design, development and testing of controllable on-chip nano-photonic elements, such as nanobeam photonic crystal filters and electro-mechanical actuators. The research into both of these types of devices presented here represents the first work of this kind that has been carried out in the LDSD group at the University of Sheffield. The majority of the measurements that have been undertaken and which are presented here are of an optical spectroscopic nature. An on-chip optical filter based on a one-dimensional photonic crystal structure has been modelled and demonstrated experimentally. Such devices can be integrated with other circuit elements in order to achieve a purely electrically driven IQOC. Tuning the resonant wavelength of the device in order to attain control over the filtering parameters has also been investigated. Control over the splitting ratio of an on-chip optical beam splitter operating at the single photon level has been achieved through an electro-mechanical cantilever based system for the first time on the GaAs platform. This technology, which can be used for switching and phase shifting, now paves the way towards the physical realization of reconfigurable IQOCs. Other more efficient and versatile electro-mechanical systems that could be used to provide greater control over a variety of optical circuit elements, such as filters and beam splitters, have also been investigated experimentally. Comb-drive actuators, which are well established on silicon based platforms, have been developed for use in the GaAs based quantum optical architecture.