Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605150
Title: Dynamics of tunable lasers in small-scale photonic integrated circuits
Author: Cemlyn, Benjamin R.
Awarding Body: University of Essex
Current Institution: University of Essex
Date of Award: 2013
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Abstract:
Mutually coupled lasers have received much attention in recent years as a source of rich non linear dynamics, enabling optical configurations for new ranges of applications, particularly chaos-based encrypted communications. However the overall dynamics of the mutually coupled configuration has not received so much attention, particularly with regard to the practical range of parameters for the lasers. This thesis investigates the dynamics of the mutually coupled lasers system in respect of all the significant causes and influences on dynamics. Furthermore, the lasers here are widely tuneable, representing the more complex tunable devices found in modern communications systems. The system investigated is both self and mutually-coupled, which represents the mechanism which may arise in modern photonic integrated circuits (PICs), and therefore has relevance to the design and operation of such devices. However the configuration here has parallels with, and great relevance to the non self-coupled configuration, and the conditions for this (such as phase) are highlighted. The dynamics are investigated experimentally in an integrated device using some of the latest technology to obtain time series of a high bandwidth, in addition to optical spectra and high resolution radio-frequency spectra. These enable a range of dynamic analysis tools such as the correlation dimension (for which a unique algorithm is described) to be applied, and this provides insight into the dynamics of the system. The PIC is also modelled using a thorough and realistic travelling wave method, which is required for the complex system of multiple coupling sources, with varying delays and optical paths which may be found in modem PICs. The PIC parameters such as coupling magnitude are first investigated experimentally and then various methods are used to calibrate these relations within the travelling wave program. A number of tuning properties of the OBR laser(s) within the PIC are then given in both the model and experiment, with good correlation between the two found. The principal investigations of dynamics in the PIC are then described. This commences with details of the overall dynamics of the PIC, and the dynamic analysis tools required to represent and quantify these dynamics. The effects of varying coupling between the lasers over a range of frequency detuning values are then studied. The effects of coupling magnitude are quantified with respect to an overall transition to chaos in the system, and overall dynamic trends. Correlation is found between the experimental and modelled results. The system of phases in the PIC are then investigated, and this has impact on the permutations of phase between oscillators in respect of conditions such as spatial symmetry and index dispersion. The control of the system of phases as a single ensemble is then described, and this is found to produce a rich variety of dynamic behaviour from this subtle parameter. Phase controlled dynamics are demonstrated experimentally, and correlated dynamics in the model are demonstrated. Finally four wave mixing, which is present in many optical configurations is shown to have a profound effect on dynamics in the model, and experimental results are presented supporting these results. These parameters of coupling magnitude, detuning, phase and four wave mixing level represent the major contributing causes of dynamics in multi-laser PICs. The results presented here have implications for the design and use of PICs, either to exploit or avoid these dynamics.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.605150  DOI: Not available
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