Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Physical Sciences

First Advisor

Dr. Guillaume Huyet

Second Advisor

Dr. Liam McDonnell


In this thesis novel stabilised ultra-fast pulse sources for a range of practical applications have been developed.

Semiconductor mode-locked lasers have much promise as sources of short, low- jitter, high repetition rate pulses. Development of stabilised semiconductor sources is in a great demand for applications, such as optical telecommunications, frequency metrology, optical sampling and clock recovery. Arbitrary waveform generation, wavelength-division and orthogonal-frequency-division multiplexing techniques need wide stable frequency combs with low phase noise. A low level of pulse-to-pulse timing fluctuations is essential for clock recovery, optical sampling and optical time- division multiplexing. Therefore, this work dealing with the development of fast stabilised quantum dot lasers is relevant across many application areas.

Recently developed mode-locked lasers, based on InAs/GaAs quantum dot material, have demonstrated advantageous performance characteristics when compared to quantum well and bulk semiconductor lasers, such as the generation of ultra- short pulses, thermal stability and low noise. Monolithic quantum dot mode-locked lasers are of particular interest due to their compactness, cost-efficiency and ease of operation. However, outside optimal parameter range these lasers suffer waveform instabilities, large chirp and significant timing jitter, which makes them ineffective in high-speed applications.

In this work, monolithic passively mode-locked lasers, based on InAs/GaAs quantum dot material, are studied and stabilised by means of external optical injection. We demonstrate that optical injection can improve the properties of mode-locked lasers in terms of the time-bandwidth product, noise and pulse stability. Finally, a cascade of quantum dot mode-locked lasers is utilised in order to (i) clone coherence and performance characteristics of the master source and (ii) to obtain high quality wider frequency combs resulting in pulses of short duration.


A thesis prepared in association with Tyndall National Institute - Photonic Device Dynamics Group

Access Level


Project Identifier

info:eu-repo/grantAgreement/HEA/ PRTLI 4//IE/Integrated NanoScience Platform for Ireland/INSPIRE

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