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Title: Wavelength stabilisation in laser diodes
Author: Huang, G.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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This thesis discusses the wavelength stabilisation of semiconductor lasers for WDM applications. The motivation is to explore the potential of a novel athermal WDM laser with much less wavelength drift than conventional lasers, and without the traditional external temperature compensation units. The study is mainly theoretical, but some experimental work is included. Based on the Cambridge time domain model, intensive simulation has been done to investigate the design space of DBR lasers. Although the structure of the initial prototype DBR model is simple, the simulation output results are rather complex. All the main parameters such as grating length, grating coupling strength, total laser cavity length and waveguide scattering loss are varied. Results obtained agree with current measurements on DBR lasers, and support dimensions and structures derived empirically. Based upon the above results, simulation work then goes further towards the athermal WDM laser idea which employs negative temperature coefficient material to physically compensate the frequency variation with temperature. A polymer widely used in optical waveguides is one candidate. Having reviewed temperature dependent parameters in semiconductor lasers, we incorporated these into the Cambridge Time Domain model. It predicts a wavelength shift of about 0.75 nm over a 100o C range at wavelength of 1500 nm where about 9nm would be expected from a normal DFB laser. It also reveals other complex and interesting behaviour, which is likely to give several useful insights into the behaviour of tuneable and other forms of DBR and BFB lasers. An experiment to verify the athermal effect of a polymer has been done. Focussed ion beam etch was employed to form a deep grating in near-conventional FP laser, and the grating voids were filled with the polymer. Lasing action with good wavelength stability was observed, though the particular structure employed is probably not capable of single mode operation over a wide temperature range.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available