Applied Physics (APHY)
We are a group of enthusiastic multidisciplinary young researchers from both the Departments of Applied Physics and Photonics (TONA) and Physics (DNTK). We use experimental and theoretical methods (nonlinear dynamics, stochastic processes, complex systems, electromagnetism, general relativity, etc.) to tackle and answer some fundamental challenges about nonlinear, complex and time-evolving systems. This combination allows an imaginative and insightful approach to problems, thereby avoiding the "fundamental-applied" polarisation. Besides photonic systems (such as e.g. semiconductor lasers) we also study other dynamical (e.g. biological) systems. The current areas of research are: - Dynamics of semiconductor lasers: nonlinear dynamics, bifurcation theory and stochastic processes are used in lasers, in particular semiconductor lasers. This theoretical study allows us to study the dynamic behaviour (e.g. bi- and multi-stability, excitability) of semiconductor lasers. These theoretical predictions are then tested experimentally in our labs. - Coherence properties of lasers: experimental and theoretical study of coherence properties of semiconductor lasers, and research into methods to modify and control the spatial coherence. In this way, we can generate spatially incoherent emission of a laser source. In our research we try to understand, model, optimize and apply this unique emission regime in innovative applications. - Metamaterials: metamaterials are complex structures that are composed of small, resonant electric circuits. These building blocks are much smaller than the wavelength of light, therefore they determine the electromagnetic properties of materials like atoms do in natural materials. Several problems are studied, ranging from the simulation of elementary metamaterial building blocks, over photonic devices based on metamaterials, to the development of metamaterial-based systems using the techniques of transformation optics. - Dissipative solitons: we study structures that arise in extended spatial systems in nature, both patterns as well as localized structures (spatial or dissipative solitons). We investigate the dynamic behaviour of these solitons (in time and space), studying the fundamental principles and unravelling the underlying bifurcation structure. - Coupled networks with delay: we study (small) networks of systems (oscillators) coupled with a time lag (delay). With such systems, synchronization may occur in which the oscillators vibrate with the same frequency and/or phase. In particular, we look at the existence and stability of such synchronized solutions and the influence of network topology and the delay. Such systems also have universal data processing properties (Reservoir Computing or Liquid State Machines) that we investigate and attempt to explain. - Non-linear oscillators with delay: We have recently shown that such systems show universal information processing properties (reservoir computing or Liquid State Machines). With only one non-linear node, we can get the same information-processing performance as with a neural network consisting of 400 nodes. We now further investigate the information processing capacity and attempt to explain and implement information processing concepts based on delay-coupled systems. - Dynamics of biological systems: we are focusing on the dynamics of toxin-antitoxin systems in bacteria and archaea. In cooperation with Structural Biology Brussels, we study models for gene regulation and function in the cell with different techniques: differential equations, stochastic methods, etc. We also study the dynamics of ecoystems, like the human gut flora (together with the Raes lab).