Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Applied Physics & Instrumentation

First Advisor

Dr. Guillaume Huyet


Rapid development of telecommunication systems forces a switch to all- optical data processing and transmission. To design such systems it is critical to understand the ultrafast processes which occur in the components of such systems, especially in Monolithic Modelocked Lasers. The purpose of this work was to identify the main physical processes influencing carrier dynamics in semiconductor nanostructures which show promise for future telecommunication systems. This study was carried out by means of ultrafast pump-probe spectroscopy, which allowed characterisation with a sub-picosecond resolution. The main part of the thesis concentrates on the analysis of the InAs/GaAs Quantum Dot (QD) system. The gain regime of optical amplifiers has already been extensively investigated while little knowledge of the behaviour of the optical amplifier in the absorption regime existed. Therefore this work focuses on an extensive study of the dynamical behaviour of optical amplifiers in the absorption regime and was studied by means of two colour pump-probe spectroscopy and accompanying numerical simulations. In addition a Tunnel Injection device operating at 1.3μm was also investigated to examine the possibility of it having improved dynamical properties over simple QD structures operating at the same wavelength. Due to the interest in structures operating at different wavelengths experiments were also performed for dilute nitride QW operating at 1.55μm and for novel AlInAs/AlGaAs QD material system operating at 800nm.


Thesis prepared in Tyndall National Institute - Photonic Device Dynamics

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