Dynamics of Semiconductor ring lasers

This thesis proposal is linked with several national and international projects and/or collaborations of the APHY group (IOLOS, PHOCUS, IAP). The overall aim is to develop, characterize and/or model the dynamic behavior of miniaturized  semiconductor lasers (SLs). Different experimental and/or theoretical subtopics can be studied.

In the last years, our group has developed a good understanding of the dynamical behavior of solitary semiconductor lasers. Nevertheless, in any real life system one SL would be a component in a larger networked structure. Using nonlinear dynamics theory and methods from computational and statistical physics, you will characterize and classify the global dynamical behavior of different network topologies. This subject can be combined with experimental work.

We recently started studying tunable semiconductor lasers in the feedback section with on-chip filtered optical feedback. These devices were designed, fabricated and characterised in a collaboration between APHY-VUB and TU/e (Eindhoven). By
controlling the current injected into the semiconductor optical amplifiers, tunable single mode operation in both directions is achieved. We now want to have a deeper understanding, both experimentally and theoretically, of the switching speed
and dynamics.

On the other hand, the presence of stochastic fluctuations in SLs represents a critical technological challenge, as well as a very interesting research track in the nonlinear physics of stochastic systems. Random field fluctuations can for instance reduce the stability of a SRL and destroy the stored information; in the same way, fluctuations are expected to unlock a wealth of dynamical regimes. The candidate will focus on the stimulating task of revealing and characterizing the effects of noise in the nonlinear dynamics of the SRL. He/she is expected to deal with the stochastic differential equations that describe the operation of an SRL in presence of noise and to predict the impact of fluctuations on different operation regimes of the laser. After completion of the project, we expect the student to have developed a fruitful "portfolio" of knowledge in the field of state of art semi-conductor laser devices, as well as competence on the general subject of stochastic differential equations, which are a broad interdisciplinary subject with potential for applications.