Dissipative temporal structures in mode-locked fibre lasers

• Applicant: Professor Dr. Jens Limpert
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5470751

The aim of this project is the fundamental study of different operation regimes of mode-locked fibre laser resonators, which may entail a complex ultrafast temporal dynamics of the output field. In the temporal domain fibre lasers are an easily accessible experimental laboratory for these investigations, because transverse field confinement separates the temporal from the spatial dynamics, the interplay of which evoke a complex spatio-temporal evolution in other laser types. Furthermore the recent progress in fibre laser technology provides laser oscillators with a large number of degrees of freedom concerning the linear and nonlinear properties of their components (i.e. filters, gain medium, saturable absorbers). Based on the understanding of the fundamental nonlinear temporal dynamics, this project will also explore the applicability of the complex operation modes identified. Our investigations will be organized in the following three work packages.The first work package is devoted to the global modelling of the phase space. In contrast to many widely used theoretical models, which were developed for the description of the system dynamics near certain bifurcation or fixed points, we aim at achieving a quite comprehensive model for a large phase and system parameter space oft he laser. This will give access to the simulation of the global system dynamics starting from cavity noise, to transient fluctuations, and finally settling on the desired temporally structured solutions, including information on the dynamic properties of the complex attractors. The price to be paid for this flexible model will consist in massive numerical simulations, which will be performed together with project A Lederer/Rockstuhl.The aim oft the second work package is the investigation of complex attractors, with major emphasis on experimental investigations. Since we are interested in complex temporal solutions, like bound states of pulses and ultrashort pulses with nontrivial phase and amplitude dynamics, attractors rather than fixed points have to be investigated. These investigations will be based on sophisticated experimental techniques like cavity filling, phase-sensitive frequency resolved optical gating, and the real time observation of ultrafast laser dynamics.In the third work package we will study concepts for the shaping oft the basin of attraction. This research is driven by the goal to experimentally realize self-starting laser operation in contrast to the non-trivial seeding techniques used in the previous work package. For this purpose the system parameters have to be modified in order to extend the basin of attraction of the desired attractors towards the noisy starting state. To this end we will study means to destabilize unwanted trivial fixed points which otherwise shield the attractors from the initial phase space.This project will advance the understanding of basic science aspects of a highly applicable system. As a consequence, the performance of these laser systems will be improved by increasing their flexibility to create complex shapes of ultrashort pulses.

• DFG Programme: Research Units
• Subproject of: FOR 532: Spatial-temporal Nonlinear Dynamics in Dissipative and Discrete Optical Systems
• Participating Person: Professor Dr. Andreas Tünnermann