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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

Oblique quasi-lossless excitation of a thin silicon slab waveguide: a guided-wave variant of an anti-reflection coating

M. Hammer, L. Ebers, J. Förstner, Journal of the Optical Society of America B (2019)

Method of superposing a multiple driven magnetic field to minimize stray fields around the receiver for inductive wireless power transmission

S. Lange, M. Büker, C. Hedayat, T. Otto, D. Sievers, J. Förstner, U. Hilleringmann, in: 13th International Conference & Exhibition on Integration Issues of Miniaturized Systems Barcelona, Spain, 10 – 11 April 2019, VDE VERLAG GMBH, 2019

This paper presents a new methodology by using a multiple coil array for energy transmission. The complex current strengths of the transmitting coil array are calculated by having the knowledge about of the mutual inductances and the symmetries of the transmitting coil array, so that its resulting magnetic field mainly penetrates only the receiving coil and is strongly attenuated outside. This method is used for an optimized wireless energy transmission but can also be implemented for other inductive applications.

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”.

Light scattering by 3-Foci convex and concave particles in the geometrical optics approximation

D. Stankevich, L. Hradyska, Y. Shkuratov, Y. Grynko, G. Videen, J. Förstner, Journal of Quantitative Spectroscopy and Radiative Transfer (2019)

We consider light scattering from a new type of model particle whose shape is represented in the form of a generalized ellipsoid having N foci, where N is greater than two. Such particles can be convex as well as concave. We use the geometrical optics approximation to study the light scattering from 3-foci particles. Non-zero elements of the scattering matrix are calculated for ensembles of randomly oriented independent transparent particles, m = n + i0. Several internal reflection orders are considered separately. It was found that the transmission-transmission (TT) and transmission-reflectance-transmission (TRT) components dominate in the formation of intensity of scattered light at large and small phase angles, respectively. We found a significant role of the total internal reflections of the TRT in the middle portion of the phase angle range. The main factors in the formation of positive linear polarization are the R and TRT component. The TT component is responsible for the formation of negative polarization branch at large phase angles.

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.

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 2019/2020: Courses, Projects

SoSe 2019 (current): Courses, Projects

WS 2018/2019: CoursesProjects

SoSe 2018: CoursesProjects

WS 2017/2018: CoursesProjects

SoSe 2017: CoursesProjects

WS 2016/2017: Courses, Projects

SoSe 2016: Courses, Projects

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