WIAS Conferences, Colloquiums, and Workshops

WORKSHOP ``DYNAMICAL SYSTEMS, SYNCHRONIZATION, LASERS''

Berlin, February 26-27

Organized by: WIAS (FG 2)

The international workshop was devoted to the following problems: Synchronization of nearly identical systems (K.R. Schneider, S. Yanchuk), forced frequency locking (M. Radziunas, L. Recke, S. Yanchuk), periodic, quasiperiodic, and chaotic regimes in lasers (S. Gonchenko, D. Rachinskii, L. Shilnikov, D. Turaev). About 20 participants from five countries attended the workshop. Seven talks were given.

WORKSHOP ``MULTISCALE SYSTEMS AND APPLICATIONS''

Berlin, April 3-5

Organized by: WIAS (FG 2), Freie Universität Berlin

Sponsored by: WIAS, DFG Research Center ``Mathematics for Key Technologies'' (FZT 86)

The workshop has been attended by 43 participants, among them 16 from abroad. Twenty-six lectures have been delivered.

During the workshop, recent trends and new results for the study of multiscale systems have been presented and discussed.

The main foci of the workshop were: phase transitions, spikes, multiscale dynamics, including delayed exchange of stability (canard solutions), control of slow-fast systems.

From the viewpoint of applications, the emphasis was on the multiscale dynamics of semiconductor lasers, of oscillating systems in biology, and of liquid film, but also models for tin-lead alloys and for micro-macro transitions have been presented.

The mathematical approaches presented in the talks to treat multiscale systems ranged from asymptotic upper and lower solutions, methods of asymptotic expansions via invariant manifolds (basing on spectral gap conditions) to the method of desingularization in case of non-hyperbolicity in singularly perturbed systems.

In the frame of control theory of systems with different time scales, problems of robust control for uncertain systems and for systems with delay as well as optimal control problems have been considered.

Two different approaches to look for invariant manifolds in stochastic systems formed a special highlight of the workshop.

WORKSHOP ``DYNAMICS OF SEMICONDUCTOR LASERS''

Berlin, September 15-17

Organized by: WIAS (FG 2), DFG Research Center ``Mathematics for Key Technologies'' (FZT 86), Ferdinand-Braun-Institut für Höchstfrequenztechnik Berlin, Fraunhofer-Institut für Nachrichtechnik Heinrich-Hertz-Institut Berlin, Humboldt-Universität zu Berlin

Sponsored by: WIAS, DFG (SFB 555, FZT 86)

During this workshop, new results have been presented from the fields of modeling, numerical simulation, and analysis of semiconductor devices, together with their applications in optical telecommunications.

Based on the financial support of the DFG Research Center ``Mathematics for Key Technologies'' (FZT 86) and the DFG Collaborative Research Center ``SFB 555: Complex Nonlinear Processes'', it was possible to invite leading experts from Europe and the USA, which made this workshop an event of high scientific significance.

Thematically, the workshop was focused on nonlinear dynamical effects in semiconductor devices. Following the tradition of preceeding workshops in 1999 and 2001, major attention was paid to an interdisciplinary approach, including the mathematical and physical background as well as technological applications, in particular optical telecommunication technologies. In the focus of interest were the subjects

delayed coupling and feedback in lasers;
mode-locked lasers and saturable absorbers;
ultrafast effects in SOAs.

From a mathematical point of view, these topics are related to bifurcation theory and pathfollowing techniques, in particular for delay differential equations, singular perturbations, synchronization, and waves in nonlinear, inhomogeneous media. Fifty-one participants attended the workshop. Twenty-six talks were given.

IVTH IMACS SEMINAR ON MONTE CARLO METHODS

Berlin, September 15-19

Organized by: WIAS (FG 6), Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB)