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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

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

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.

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)

Oblique evanescent excitation of a dielectric strip: A model resonator with an open optical cavity of unlimited Q

M. Hammer, L. Ebers, J. Förstner, Optics Express (2019), 27(7), pp. 8

A rectangular dielectric strip at some distance above an optical slab waveguide is being considered, for evanescent excitation of the strip through the semi-guided waves supported by the slab, at specific oblique angles. The 2.5-D configuration shows resonant transmission properties with respect to variations of the angle of incidence, or of the excitation frequency, respectively. The strength of the interaction can be controlled by the gap between strip and slab. For increasing distance, our simulations predict resonant states with unit extremal reflectance of an angular or spectral width that tends to zero, i.e. resonances with a Q-factor that tends to infinity, while the resonance position approaches the level of the guided mode of the strip. This exceptionally simple system realizes what might be termed a “bound state coupled to the continuum”.

    Optical transition between two optical waveguides layer and method for transmitting light

    M. Hammer, J. Förstner, L. Ebers. Optical transition between two optical waveguides layer and method for transmitting light, Patent DE102018108110B3. 2019.

    The invention relates to an optical junction between two optical planar waveguides. For this purpose, an arrangement is provided of a first optical layer waveguide (2) and a second optical slab waveguide (3), wherein the first optical layer waveguide (2) and the second optical slab waveguide (3) different from each other is constant over their respective length of thicknesses (d, r ) which the first optical layer waveguide (2) with the second optical film waveguide (3) (by means of an optical layer waveguide structure 4) is connected, which (along their entire length w) has a thickness (h) which is between the thickness (d) the first optical waveguide layer (2) and the thickness (r) of the second optical waveguide layer (3). According to the invention, the thickness (h) of the optical layer waveguide structure (4) over the entire length (w) of the optical layer waveguide structure (4) constant. Thus, a possibility for an efficient and entailing low loss transition between two optical planar waveguides is provided with different thickness.

      Coupled microstrip-cavities under oblique incidence of semi-guided waves: a lossless integrated optical add-drop filter

      L. Ebers, M. Hammer, M.B. Berkemeier, A. Menzel, J. Förstner, OSA Continuum (2019)

      We investigate optical microresonators consisting of either one or two coupled rectangular strips between upper and lower slab waveguides. The cavities are evanescently excited under oblique angles by thin-film guided, in-plane unguided waves supported by one of the slab waveguides. Beyond a specific incidence angle, losses are fully suppressed. The interaction between the guided mode of the cavity-strip and the incoming slab modes leads to resonant behavior for specific incidence angles and gaps. For a single cavity, at resonance, the input power is equally split among each of the four output ports, while for two cavities an add-drop filter can be realized that, at resonance, routes the incoming power completely to the forward drop waveguide via the cavity. For both applications, the strength of the interaction is controlled by the gaps between cavities and waveguides.

      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

      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: CoursesProjects

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