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Welcome to the Theoretical Electrical Engineering group (TET)

Our main research interest is the theoretical description of photonic and optoelectronic systems like optical nanoantennas, dielectric waveguides, photonic crystals, metamaterials, plasmonic systems, or biological photonic structures. Our speciality is the combinations of advanced material models with state-of-the-art numerical methods for the simulation of electromagnetic fields. For students we offer a wide range of courses ranging from the theoretical foundation of electromagnetism and numerics to advanced courses on field simulation and photonics. 

Research: Topics, Publications, Team

Teaching: Course Portfolio, Current Courses, Current Projects


The five most recent publications

Open list in Research Information System

HighPerMeshes – A Domain-Specific Language for Numerical Algorithms on Unstructured Grids

S. Alhaddad, J. Förstner, S. Groth, D. Grünewald, Y. Grynko, F. Hannig, T. Kenter, F. Pfreundt, C. Plessl, M. Schotte, T. Steinke, J. Teich, M. Weiser, F. Wende, in: Euro-Par 2020: Parallel Processing Workshops, 2021

Solving partial differential equations on unstructured grids is a cornerstone of engineering and scientific computing. Nowadays, heterogeneous parallel platforms with CPUs, GPUs, and FPGAs enable energy-efficient and computationally demanding simulations. We developed the HighPerMeshes C++-embedded Domain-Specific Language (DSL) for bridging the abstraction gap between the mathematical and algorithmic formulation of mesh-based algorithms for PDE problems on the one hand and an increasing number of heterogeneous platforms with their different parallel programming and runtime models on the other hand. Thus, the HighPerMeshes DSL aims at higher productivity in the code development process for multiple target platforms. We introduce the concepts as well as the basic structure of the HighPerMeshes DSL, and demonstrate its usage with three examples, a Poisson and monodomain problem, respectively, solved by the continuous finite element method, and the discontinuous Galerkin method for Maxwell’s equation. The mapping of the abstract algorithmic description onto parallel hardware, including distributed memory compute clusters, is presented. Finally, the achievable performance and scalability are demonstrated for a typical example problem on a multi-core CPU cluster.

    Light backscattering from large clusters of densely packed irregular particles

    Y. Grynko, Y. Shkuratov, J. Förstner, Journal of Quantitative Spectroscopy and Radiative Transfer (2020), 255, pp. 107234

    We numerically simulate multiple light scattering in discrete disordered media represented by large clusters of irregular non-absorbing particles. The packing density of clusters is 0.5. With such conditions diffuse scattering is significantly reduced and light transport follows propagation channels that are determined by the particle size and topology of the medium. This kind of localization produces coherent backscattering intensity surge and enhanced negative polarization branch if compared to lower density samples.

    Light diffraction in slab waveguide lenses simulated with the stepwise angular spectrum method

    L. Ebers, M. Hammer, J. Förstner, Optics Express (2020), 28(24), pp. 36361

    A stepwise angular spectrum method (SASM) for curved interfaces is presented to calculate the wave propagation in planar lens-like integrated optical structures based on photonic slab waveguides. The method is derived and illustrated for an effective 2D setup first and then for 3D slab waveguide lenses. We employ slab waveguides of different thicknesses connected by curved surfaces to realize a lens-like structure. To simulate the wave propagation in 3D including reflection and scattering losses, the stepwise angular spectrum method is combined with full vectorial finite element computations for subproblems with lower complexity. Our SASM results show excellent agreement with rigorous numerical simulations of the full structures with a substantially lower computational effort and can be utilized for the simulation-based design and optimization of complex and large scale setups.

      Electrically controlled rapid adiabatic passage in a single quantum dot

      A. Mukherjee, A. Widhalm, D. Siebert, S. Krehs, N. Sharma, A. Thiede, D. Reuter, J. Förstner, A. Zrenner, Applied Physics Letters (2020), 116, pp. 251103

      Hybrid coupled mode modelling of the evanescent excitation of a dielectric tube by semi-guided waves at oblique angles

      M. Hammer, L. Ebers, J. Förstner, Optical and Quantum Electronics (2020), 52

      A dielectric step-index optical fiber with tube-like profile is considered, being positioned with a small gap on top of a dielectric slab waveguide. We propose a 2.5-D hybrid analytical/numerical coupled mode model for the evanescent excitation of the tube through semi-guided waves propagating in the slab at oblique angles. The model combines the directional polarized modes supported by the slab with analytic solutions for the TE-, TM-, and orbital-angular-momentum (OAM) modes of the tube-shaped fiber. Implementational details of the scheme are discussed, complemented by finite-element simulations for verification purposes. Our results include configurations with resonant in-fiber excitation of OAM modes with large orbital angular momentum and strong field enhancement.

        Max number of publications reached - all publications can be found in our Research Infomation System.

        Open list in Research Information System

        Head of the group

        Prof. Dr. Jens Förstner

        Theoretical Electrical Engineering

        Jens Förstner
        +49 5251 60-3013
        +49 5251 60-3524

        Office hours:

        on request (during lecture break)

        TET courses & projects

        Frequently asked questions (FAQ)

        Course Portfolio

        SoSe 2021: Courses, projects

        WS 2020/2021: Courses, projects

        SoSe 2020: Courses, projects

        WS 2019/2020:Courses, projects

        SoSe 2019: Courses, projects

        WS 2018/2019: Courses, projects

        SoSe 2018: Courses, projects

        WS 2017/2018: Courses, projects

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