Computational Nanophotonics

Within the framework of the Emmy-Noether Junior Research Group "Computational Nanophotonics", a large number of individual questions from the field of photonic nanostructures were investigated using quantitative simulations. The overall success of the chosen approach has been shown to be a combination of microscopic material models (density matrix theory for semiconductors, hydrodynamic model for metals excited below the band gap) with numerical methods for solving the 3D Maxwell equations (FDTD, DG-TD). For semiconductor quantum dots that could interact with localized modes of defect cavities in photonic crystals, normal mode splitting was demonstrated microscopically and quantitatively. For combination of several such systems, the Einfluss of the arrangement could be determined. For quantum dots in microdisk resonators in a liquid crystal, the Einfluss of the variable anisotropic dielectric environment could be simulated and showed good agreement with experiment. For quantum dot molecules, it was shown how the tunneling rate between quantum dot states can be significantly enhanced by the Einfluss of the lattice environment in the form of photons. The Einfluss of phonons is also clearly seen in adiabatic transitions between singlet states of the quantum dot molecule. A work in quantum optics in cooperation with S. Schumacher showed how a biexciton decay process can be massively enhanced via a virtual intermediate state by suitable setting of a photonic, so that it becomes the dominant process. The relatively long duration of the project also allowed for an interesting but costly method development, which was started with uncertain prospects of success. Based on a dynamic time-dependent density functional theory, the nonlinear response of metallic nanostructures was described. With this approach it could be confirmed that Second Harmonic Generation is generated at the Oberfläche of nanostructures, but in a nonclassical since nonlocal way. The relevant length scales could be extracted and used as a reference and basis for numerically handier semiclassical approaches such as the Fermi pressure model. Another focus was the development of numerical methods for the simulation of electromagnetic field propagation in nanostructures in combination with microscopic material models. Here, on the one hand, the widely used FDTD was built upon, which could be extended by various material models with stable and convergent simulation. A breakthrough was also made possible by the complex implementation of a simulation tool based on the Nodal Discontinuous Galerkin Time Domain method, which allows adaptive grids and shows better dispersion behavior as a higher order method. Only this allowed the reliable simulation of higher harmonic generation in nanostructures in the framework of an extended hydrodynamic model. For arrays of plasmonic split-ring resonators, it was shown that at too high densities the SHG efficiency is reduced by damping effects and field deformations. Thus, overall, a variety of interesting photonic nanostructures in the linear and nonlinear excitation range could be successfully described using the developed theories based on microscopic material models and field simulation methods.

Publications

"Self-assembled quantum dots in a liquid-crystal-tunable microdisk resonator", Physica E 42, 2552 (2010)

Karoline A. Piegdon, Matthias Offer, Axel Lorke, Martin Urbanski, Andreas Hoischen, Heinz-S. Kitzerow, Stefan Declair, Jens Förstner, Torsten Meier, Dirk Reuter, Andreas D. Wieck, Cedrik Meier

"Indirect spin dephasing via charge-state decoherence in optical control schemes in quantum dots", Phys. Rev. A 79, 042331 (2009)

A. Grodecka, P. Machnikowski, and J. Förstner

"Anticrossing of Whispering Gallery Modes in Microdisk Resonators Embedded in an Anisotropic Environment", Photonics and Nanostructures - Fundamentals and Applications 8, 273-277 (2010)

S. Declair, C. Meier, T. Meier, J. Förstner

"Enhanced FDTD Edge Correction for Nonlinear Effects Calculation“, Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE, 1-4 (2010)

C. Classen, J. Förstner, T. Meier, R. Schuhmann

"Tuning quantum-dot based photonic devices with liquid crystals", Optics Express, 18, 7946 (2010)

Karoline A. Piegdon, Stefan Declair, Jens Förstner, Torsten Meier, Heiner Matthias, Martin Urbanski, Heinz-S. Kitzerow, Dirk Reuter, Andreas D. Wieck, Axel Lorke, Cedrik Meier

“Reversal of coherently controlled ultrafast photocurrents by band mixing in undoped GaAs semiconductor quantum wells“, Phys. Rev. Lett. 104, 217401 (2010)

S. Priyadarshi, A.M. Racu, K. Pierz, U. Siegner, M. Bieler, H.T. Duc, J. Förstner, T. Meier

“Simulation of the ultrafast nonlinear optical response of metal slabs”, phys. stat. sol. (b) 248, 887 (2011)

Mathias Wand, Arno Schindlmayr, Torsten Meier, Jens Förstner

"Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with fine-structure splitting", Optics Express 20, 5335 (2012)

Stefan Schumacher, Jens Förstner, Artur Zrenner, Matthias Florian, Christopher Gies, Paul Gartner, and Frank Jahnke

"Collective effects in second-harmonic generation from split-ring-resonator arrays", Phys. Rev. Lett. 109, 15502 (2012)

S. Linden, F.B.P. Niesler, J. Förstner, Y. Grynko, T. Meier, M. Wegener

"Photonic Crystal Waveguides Intersection for Resonant Quantum Dot Optical Spectroscopy Detection", Optics Express 20, 14130 (2012)

Xiaohong Song, Stefan Declair, Torsten Meier, Artur Zrenner, Jens Förstner