Date of Award

2014

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Physical Sciences

First Advisor

Dr Guillame Guyet

Abstract

With the rapid commercialization of personal computers and with the ever increasing desire for faster and larger data transfer, there is a strong need to increase network capacity. One solution is to replace standard metallic connections by optical fibers and full optical technologies. Although such technologies exist and are successfully employed in backbone connections, their complexities hinder a wider utilization toward end customers. Therefore, both manufacturing and operational costs are crucial. Integration of several optical components onto a single device chip is the key element. A simplified integration scheme bringing an additional cost reduction is also welcomed. This thesis presents the characterization of electro-optic and lasing properties of several novel material systems based on hybrid QD-QW nanostructures. Thanks to these hybrid systems, a simplified integration scheme, called identical active layer, is used, where fabrication involves only epitaxial growth without any postgrowth treatment. These hybrid materials could be utilized in fast reconfigurable multisection devices where each section could play a different role, i.e. provide gain or variable attenuation, leading to electro-modulated lasers generating a return-to-zero modulation format. Extensive work is also focused on the characterization of two QW nanostructures based on quaternary semiconductor alloys, firstly, the GaInNAs system and secondly, the GalnAsSb system. These nanostructures enable an extension of the operational range in terms of wavelength up to 1310 nm and being a GaAs-based semiconductor, offer better thermal performances over InP without the need for active external cooling. This brings further cost reductions and increases device yield in comparison with the state-of the art Mach-Zehnder modulators currently used. A sufficient shift of the nanostructures absorption edges, reaching up to 40 nm, led to an extinction ratios of 9 dB and more. Together with sub-10 ps carrier dynamic recoveries, the nanostructures are very promising for massive employment in last mile optical networks.

Access Level

info:eu-repo/semantics/openAccess

Project Identifier

info:eu-repo/grantAgreement/SFI/Strategic Research Cluster/07/SRC/I1173/IE/Photonics - Integration From Atoms to Systems/PiFAS

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