Optical Injection in Semiconductor Ring Lasers

Student thesis: Master's Thesis


Semiconductor ring lasers distinguish themselves from other semiconductor lasers by their circular waveguide cavity, wich enables them to lase in two counterpropagating directions. Their typical waveguide structure makes them very suitable for monolithic integration in "on-chip" applications, and their bistable character enables them to be employed as all-optical memories and switching devices in fully integrated all-optical networks.
This thesis theoretically investigates the dynamical behavior of a semiconductor ring laser when it is optically injected by light from an external laser source. Optical injection has important applications such as spectral linewidth reduction and wavelength conversion, and the deployment of semiconductor ring lasers in all-optical applications actually relies on their response to an optically injected pulse.
We use a well-established rate equation model for the semiconductor laser that is known to adequately model its dynamical behavior. Keeping in mind the all-optical memory applications, we focus on unideirctional optical injection - i.e. optical infection in one of the two counterpropagating modes. This will also facilitate comparison of our results with future experiments. Numerical simulations of this model yield several results such as an alternative route to stable locking (with respect to Fabry-PĂ©rot cavity lasers) and an anti-phase chaotic regime at low injection power. In order to get more information about how these arise we also perform a bifurcation analysis using the continuation software package AUTO. Furthermore, we investigate the influence of a parameter which is uncontrollable during the fabrication process - the backscattering phase - on the optical injection dynamics.
We derive an asymptotic reduced model based on the occurrence of different time scales in the system, eliminating the fast relaxation oscillation time scale. This way we are able to asymptotically reduce the dimension of our system from five to three. We use the three-dimensional phase space introduced by this model in order to interpret the results obtained by the (full) five-dimensional model. Using this model, we are a.o. able to draw parallels between the optically injected semiconductor laser and a well-know, exemplary dynamical system: the periodically forced Duffing oscillator.
Finally, using our reduced model, we analytically investigate the case of zero backscattering. This particular situation corresponds to the case of high bias currents, which are typically used in engineering applications. We obtain a good agreement with numerical simulations.
Date of Award2009
Original languageEnglish
SupervisorJan Danckaert (Promotor), Stefano Beri (Jury), Guy Van Der Sande (Jury), Guy Verschaffelt (Jury), Thomas Erneux (Jury) & Yves Rolain (Jury)


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