Dr. Manfred Hammer

Paderborn University

Theoretical Electrical Engineering

Warburger Strasse 100

33098 Paderborn

Germany

Phone: ++49 (0)5251/60-3560

Fax: ++49 (0)5251/60-3524

Building P1, room P1.5.17.1

Paderborn University

Theoretical Electrical Engineering

Warburger Strasse 100

33098 Paderborn

Germany

Phone: ++49 (0)5251/60-3560

Fax: ++49 (0)5251/60-3524

Building P1, room P1.5.17.1

Dr. Manfred Hammer

Universität Paderborn

FG Theoretische Elektrotechnik

Warburger Straße 100

33098 Paderborn

Tel: 05251/60-3560

Fax: 05251/60-3524

Gebäude P1, Raum P1.5.17.1

Universität Paderborn

FG Theoretische Elektrotechnik

Warburger Straße 100

33098 Paderborn

Tel: 05251/60-3560

Fax: 05251/60-3524

Gebäude P1, Raum P1.5.17.1

E-mail: manfred.hammer@uni-paderborn.de

Research topics: Things we have
been / are busy with, including a bunch of figures.
Keywords:
Theoretical photonics, integrated optics, numerical modeling;
dielectric waveguide theory, mode solvers; interferometric devices,
nonreciprocal integrated optical devices;
polarizer / isolator / circulator concepts; microresonator simulations ...

Publications: References to journal papers, book chapters, and
contributions to conference proceedings, a list of talks and poster
presentations, and links to postscript versions of my PhD- and Diploma
theses.

Teaching: Information about the courses and MSc projects
(finished and upcoming) where I am involved in.

Metric:
Tools for semianalytic modeling in integrated optics /
photonics, simulations of lossless 2D configurations with rectangular
refractive index distributions. Includes a mode solver
engine for dielectric multilayer slab waveguides, and solvers for scalar and vectorial guided-wave
Helmholtz (-scattering) problems based on spectral discretizations along one
(BEP: bidirectional eigenmode propagation)
or two coordinate axes
(QUEP: quadridirectional eigenmode propagation).
Extensions concern the angled propagation of plane waves across dielectric multilayer stacks, conventional and hybrid analytical/numerical variants of coupled mode theory, a 2-to-1D
effective index treatment of 2D scattering problems, a variational effective-index-like mode solver for 3D channels (with 2D cross sections), the computation of Floquet-Bloch-modes
for rectangular periodic structures in 2D, and solvers for the bend modes of curved slab structures, the whispering gallery modes supported by 2-D circular multilayer dielectric cavities, and the guided modes of circular multi-step-index optical fibers.
A series of application examples, embedded in the html manual, complements the downloadable, commented C++ sources.

WMM:
A quasianalytic mode
solver for rectangular dielectric integrated optical waveguide channels
(3D configurations with 2D cross sections). Besides the actual procedures for guided mode analysis, the programs
provide facilities for the evaluation of perturbational expressions, and an implementation of coupled mode theory.
The html manual includes the downloadable, commented C++ sources, accompanied by several application examples.

OMS: A mode solver for optical
dielectric multilayer slab waveguides with 1D cross sections. Following the
waveguide definition in terms of refractive indices, layer thicknesses, and
the vacuum wavelength, the script calculates the propagation
constants / effective indices of guided modes and allows to inspect the
corresponding optical field patterns.
Facilities for evaluating simple parameter scans
(modal dispersion properties) are provided.
The solver is intended as a basic tool for
integrated optics design, in particular for purposes of demonstration.

EIMS: Similar to its
1D counterpart, this script calculates and visualizes the guided fields of
dielectric integrated optical waveguides with two-dimensional light confinement
and weak lateral guiding. Note the remarks on the variant of the effective-index approximation
the mode solver relies on.

FiMS:
An online solver for the guided modes supported by circular dielectric optical fibers with radially piecewise constant refractive index profiles. Following the fiber definition in terms of vacuum wavelength, core radius, refractive indices, and thicknesses of intermediate layers, the script calculates the effective mode indices and propagation constants of the vectorial, hybrid guided modes supported by the fiber. TE- and TM-modes can be identified, as well as orbital-angular-momentum (OAM) modes of different angular and radial orders; modes of EH- and HE-type are found as superpositions of the latter. Facilities for detailed inspection of the mode profiles, and for exporting data and figures, are provided.

MuLS:
A solver for problems of plane wave reflection from dielectric multilayer systems at oblique incidence. Given the stack definition in terms of refractive indices, layer thicknesses, vacuum wavelength, and the angle of incidence, the script calculates reflectance and transmittance properties for s- and p-polarized waves, and allows to inspect the corresponding optical fields. Facilities for evaluating parameter scans / spectra are available. The script can serve as a basic tool for the design of dielectric multilayer coatings / reflectors / filters, in particular for purposes of demonstration.

BendS:
A mode solver for bent integrated optical multilayer slab waveguides and curved dielectric interfaces with 1-D cross sections. Following the structure definition in terms of bend radius, refractive indices, layer thicknesses, if applicable, and the vacuum wavelength, the script calculates the complex effective indices of the leaky modes supported by the bend, or their phase propagation and attenuation constants, respectively, and allows to inspect the corresponding bend mode profiles. Optical field patterns associated with the bend mode propagation can be visualized directly.

WGMs:
An online solver for the whispering gallery resonances of microdisks, microrings, or more general circular 2-D dielectric multilayer cavities in integrated optics / photonics. Following the structure definition in terms of cavity radius, refractive indices, and layer thicknesses, if applicable, and the specification of a target vacuum wavelength or of an interval of potential resonance wavelengths, the script calculates the complex angular eigenfrequencies of the (leaky) whispering gallery modes supported by the cavity, and their resonance wavelengths and linewidths, resonance frequencies, cavity lifetimes, and quality (Q-) factors, respectively. Facilities for detailed inspection of the corresponding mode profiles and resonant field patterns, and for exporting data and figures, are provided.

QuEPS: A frequency domain solver for 2-D rectangular optical guided-wave scattering problems. The scalar polarized 2-D Helmholtz equations are addressed, on a rectangular computational domain with transparent boundary conditions that permit guided wave in- and outflux. Following the problem specification in terms of interface positions, a matrix of refractive index values, polarization and wavelength parameters, and guided wave input, the script determines modal output amplitudes (elements of the scattering matrices), and the power levels associated with guided and nonguided directional outgoing waves (transmittances / reflectances, power balance). Facilities for detailed inspection of the optical electromagnetic field are provided, including animations of the harmonic oscillations in time, with options for exporting figures and data.

WaFE: Conversion between quantities that characterize the propagation of harmonic electromagnetic waves in vacuum.
This concerns wavelength, wavenumber, spectroscopic wavenumber, frequency, angular frequency, time period, and photon energy, (mostly) in SI units.

Plot-It: An online function and data plotter.
Features: graphs of functions of one variable, data curves, parametrized functions, families of functions, cubic spline interpolation, linear regression; export to svg-images, aims at a close-to-scientific appearance of the figures.

Teval: A script that can
evaluate simple C-style expressions. The script knows about the numerical
values of some common physical constants, hence it is in particular useful
for a certain class of basic exercises in physics courses ...

Bookmarks: Links that I find nice or useful
or that I once found nice or useful.