Abstract
The goal of this thesis is twofold: to theoretically study the dynamical behaviour of semi-conductor lasers under the influence of optical feedback, and to show several new device concepts that exploit this dynamics for applications in advanced optical communication networks. In the beginning of my PhD work, while at UIB, I participated in the project "Photonic Integrated Components Applied to Secure chaoS encoded Optical communications systems" (PICASSO), whose goal was to generate a highly chaotic waveform for encryption purposes using integrated SLs subject to optical feedback. In the second chapter of this thesis a novel T-shaped laser is presented to investigate chaotic synchronization and data transmission. The motivation behind this work is to realize encryption on the hardware level. Combined with more traditional software encryption, the security can be signi?cantly increased.Chaotic dynamics is usually to be avoided when a stable device operation is required. However, chaos is useful for particular applications. Our control technique based on ?ltered optical feedback in T-shaped SLs is important because it ?nds applications in data transmission systems when a damage of ?ber occurs and optical feedback may result in non desired system behaviour. This application is investigated in the third chapter of this thesis.
The work presented in the fourth chapter is devoted to a theoretical study the dynamics of semiconductor ring lasers (SRLs) under influence of optical feedback. SRLs are promising components in photonic integrated circuits (PICs). However, a considerable amount of feedback from other components is expected when a SRL is integrated in a PIC. Therefore, we study the potentially detrimental effect of such feedback in this work. We numerically show that if the feedback symmetry is broken, SRLs may exhibit complex dynamics that can be explained by the (some of the?) external cavity modes becoming unstable.
In the last part of my PhD work, I am involved in a joint project between TU Eindhoven (TU/e, Netherlands) and VUB, called EFFECT (Exploiting Filtered Feedback in Controlling Tunable lasers). In the framework of this project the concept of a novel integrated tunable laser is proposed by and fabricated in Eindhoven. At VUB we develop a model, allowing to study the in?uence of the device parameters and especially the feedback phase on the successful tuning of the laser wavelength and the switching speed. We introduce the concept of effective losses to explain the different switching mechanisms in the device. Our predictions are compared to measurements on the first batch of devices fabricated at TU/e.
Date of Award | 4 May 2011 |
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Original language | English |
Supervisor | Jan Danckaert (Promotor), Stefano Beri (Co-promotor) & Claudio R. Mirasso (Co-promotor) |
Keywords
- photonics
- semiconductor lasers