Prof. Stefanie Kroker Profile

Prof. Stefanie Kroker

at Technische Univ Braunschweig

SPIE Involvement:

Conference Program Committee | Author

Publications (25)

Proceedings Article | 18 June 2024 Presentation

Advanced evaluation of imaging Mueller matrix ellipsometry

Tim Käseberg, Jana Grundmann, Thomas Siefke, Stefanie Kroker, Bernd Bodermann

Proceedings Volume 12997, 1299706 (2024) https://doi.org/10.1117/12.3021873

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Proceedings Article | 5 October 2023 Open Access

From atoms to black holes: with nano-engineering to next-level precision experiments

Stefanie Kroker

Proceedings Volume PC12653, PC1265302 (2023) https://doi.org/10.1117/12.2688839

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Proceedings Article | 28 September 2023 Presentation + Paper

Towards next-generation ultrastable lasers with microstructured mirrors

Johannes Dickmann, Steffen Sauer, Stefanie Kroker

Proceedings Volume 12665, 1266503 (2023) https://doi.org/10.1117/12.2676646

KEYWORDS: Mirrors, Fabry–Perot interferometers, Scattered light, Laser microstructuring, Micromirrors, Silicon, Silica, Light scattering, Laser applications

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Proceedings Article | 23 August 2023 Presentation

Simulating achromatic plasmonic lenses with inverted design for improved nano-optics

Tim Käseberg, Stefanie Kroker, Bernd Bodermann

Proceedings Volume PC12619, PC1261909 (2023) https://doi.org/10.1117/12.2673769

KEYWORDS: Plasmonics, Lenses, Design and modelling, Nano optics, Flat optics, Integrated optics, Fabrication, Surface plasmon polaritons, Spectroscopy, Numerical simulations

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Proceedings Article | 27 October 2021 Paper

Ellipsometric characterizations of individual nanoform structures

Tim Kaeseberg, Jana Grundmann, Sven Teichert, Matthias Wurm, Thomas Siefke, Stefanie Kroker, Bernd Bodermann

Proceedings Volume 11927, 119270O (2021) https://doi.org/10.1117/12.2616273

KEYWORDS: Ellipsometry, Polarization, Nanostructures, Cameras, Optical testing, Objectives, Imaging systems, Scanning electron microscopy, Nanolithography, Microscopes

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Proceedings Article | 12 September 2021 Presentation

Optical nanoform characterization by imaging Mueller matrix ellipsometry

Tim Käseberg, Jana Grundmann, Thomas Siefke, Stefanie Kroker, Bernd Bodermann

Proceedings Volume 11876, 118760C (2021) https://doi.org/10.1117/12.2599853

KEYWORDS: Ellipsometry, Imaging systems, Nanostructures, Inverse optics, Statistical analysis, Polarization, Microscopy, Microscopes, Silicon, Ranging

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Using conventional Mueller matrix ellipsometry, the geometries of periodic nanostructures can be easily determined if the measurement fields are not smaller than the illumination spot size. Measurements on individual nanostructures smaller than this can be accounted for by imaging ellipsometry, which allows measuring all 16 Mueller matrix elements for each pixel in the camera of the imaging system. These so-called Mueller matrix images contain additional information about the spatial distribution of the sample’s polarizing properties that are useful in the characterization of individual nanostructures. We built an imaging Mueller matrix ellipsometry system for measurements in the visible regime. Our system allows for the analysis arm, which holds the CCD camera and the polarization state analyser, to be rotated freely around the sample. By this, measurements in reflection and in transmission can be performed at arbitrary angles of incidence between 37.5° and 90°. Additionally, we implemented a reflection mode for 0° angle of incidence. Using this setup, our goal is to characterize the shape of individual nanostructures much smaller than the illumination spot using the additional information from the Mueller matrix images. Thus, we designed and fabricated a sample containing various individual nanostructures with different geometrical features. The structures are of square or circular shape, ranging in size from 5 µm to 50 nm. Additionally, the square structures feature corner rounding with different radii for a transition between circle and square. With these structures, we systematically measure the influence of the shape on the Mueller matrix elements. We also investigate in using Mueller matrix images for the characterization of subwavelength sized features significantly smaller than the resolution limit of our microscope system at about 800 nm. First results show clear distinctions between opposing edges of the nanostructures in off-diagonal Mueller matrix images.

Proceedings Article | 20 June 2021 Open Access

Heat dynamics in optical ring resonators

Walter Dickmann, Lukas Max Weituschat, René Eisermann, Stephan Krenek, Pablo Aitor Postigo, Stefanie Kroker

Proceedings Volume 11783, 1178309 (2021) https://doi.org/10.1117/12.2592552

KEYWORDS: Resonators, Absorption, Waveguides, Silicon, Chemical elements, Thermography, Temperature metrology, Silica, Sensors, Geometrical optics

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Proceedings Article | 20 June 2021 Presentation

Applicability simulations of inverted plasmonic lenses

Tim Käseberg, Thomas Siefke, Jana Grundmann, Stefanie Kroker, Bernd Bodermann

Proceedings Volume 11783, 117830E (2021) https://doi.org/10.1117/12.2591098

KEYWORDS: Lenses, Plasmonics, Near field scanning optical microscopy, Optical microscopy, Nanostructures, Diffraction, Dielectrics, Visible radiation, Surface plasmon polaritons, Super resolution microscopy

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Proceedings Article | 5 March 2021 Presentation

Towards optically pumped GaN-based high-contrast grating V(E)CSELs

Frederik Luessmann, Jana Hartmann, Hergo-Heinrich Wehmann, Constantin Hilbrunner, Joerg Malindretos, Angela Rizzi, Stefanie Kroker, Andreas Waag

Proceedings Volume 11706, 117061I (2021) https://doi.org/10.1117/12.2578577

KEYWORDS: Optical pumping, Quantum wells, Mirrors, Mirror structures, Absorption, Vapor phase epitaxy, Scattering, Scanning transmission electron microscopy, Scanning electron microscopy, Reflectometry

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Proceedings Article | 22 July 2019 Paper

Method for non-invasive hemoglobin oxygen saturation measurement using broadband light source and color filters

Wenze Wu, Finn-Niclas Stapelfeldt, Thomas Weimann, Peter Hinze, Thorsten Dziomba, Bernd Bodermann, Stefanie Kroker, Hutomo Suryo Wasisto, Andreas Waag

Proceedings Volume 11076, 110761S (2019) https://doi.org/10.1117/12.2527202

KEYWORDS: Optical filters, Light sources, Image sensors, Sensors, Light emitting diodes, Oxygen, Oximetry, Tissue optics, Signal detection, Signal processing

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Proceedings Article | 21 June 2019 Open Access

Mueller matrix ellipsometry for enhanced optical form metrology of sub-lambda structures

Tim Käseberg, Johannes Dickmann, Thomas Siefke, Matthias Wurm, Stefanie Kroker, Bernd Bodermann

Proceedings Volume 11057, 110570R (2019) https://doi.org/10.1117/12.2527419

KEYWORDS: Plasmonics, Ellipsometry, Scanning electron microscopy, Numerical simulations, Metrology, Nanostructures, Near field optics

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Proceedings Article | 21 June 2019 Presentation + Paper

Modeling aspects for high precision absorption measurements

Walter Dickmann, Johannes Dickmann, Florian Bruns, Stefanie Kroker

Proceedings Volume 11057, 110570B (2019) https://doi.org/10.1117/12.2525690

KEYWORDS: Absorption, Refractive index, Modulation, Precision measurement, Refraction, Spatial resolution, Photothermal effect

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Proceedings Article | 24 May 2018 Presentation + Paper

Determination of structural deviations in wire grid polarizers for DUV application wavelengths by transmission spectroscopy in the visible spectral range

T. Siefke, W. Dickmann, T. Weichelt, M. Steinert, J. Dickmann, C. B. Rojas Hurtado, B. Bodermann, S. Kroker

Proceedings Volume 10678, 106780O (2018) https://doi.org/10.1117/12.2306026

KEYWORDS: Polarizers, Transmittance, Deep ultraviolet, Double patterning technology, Visible radiation, Ion beams, Etching, Spectroscopy, Chromium, Polarization

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Proceedings Article | 26 June 2017 Paper

Simulation of the influence of line edge roughness on the performance of deep ultraviolet wire grid polarizers

Thomas Siefke, Carol Rojas Hurtado, Johannes Dickmann, Martin Heusinger, Stefanie Kroker

Proceedings Volume 10330, 103300S (2017) https://doi.org/10.1117/12.2269602

KEYWORDS: Refractive index, Finite-difference time-domain method, Tungsten, Ion beams, Etching, Deep ultraviolet, Polarization, Modeling, Line edge roughness, Polarizers, Optical metrology, Polarization control

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Proceedings Article | 31 October 2016 Paper

Anti-reflective sub-wavelength structures at a wavelength of 441.6 nm for phase masks of near-field lithography

Jinyu Li, Huoyao Chen, Stefanie Kroker, Thomas Käsebier, Zhengkun Liu, Keqiang Qiu, Ying Liu, Ernst-Bernhard Kley, Xiangdong Xu, Yilin Hong, Shaojun Fu

Proceedings Volume 10022, 100220T (2016) https://doi.org/10.1117/12.2246381

KEYWORDS: Electron beam lithography, Antireflective coatings, Lithography, Near field, Photomasks, Interfaces, Reflectivity, Glasses, Diffraction, Stray light

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Proceedings Article | 31 October 2016 Paper

Design of soft x-ray varied-line-spacing grating based on electron beam lithography-near field lithography

Dakui Lin, Huoyao Chen, Stefanie Kroker, Thomas Käsebier, Zhengkun Liu, Keqiang Qiu, Ying Liu, Ernst-Bernhard Kley, Xiangdong Xu, Yilin Hong, Shaojun Fu

Proceedings Volume 10022, 100220S (2016) https://doi.org/10.1117/12.2246356

KEYWORDS: Lithography, X-rays, Silica, Photomasks, X-ray lithography, Electron beam lithography, Optical design, Electron beams, Photoresist materials, Diffraction

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Proceedings Article | 15 September 2016 Presentation + Paper

Design and fabrication of titanium dioxide wire grid polarizer for the far ultraviolet spectral range

Thomas Siefke, Ernst-Bernhard Kley, Andreas Tünnermann, Stefanie Kroker

Proceedings Volume 9927, 992706 (2016) https://doi.org/10.1117/12.2237644

KEYWORDS: Titanium dioxide, Polarizers, Far ultraviolet, Transmittance, Titanium, Refractive index, Polarization, Photomasks, Electron beam lithography, Diffraction

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Proceedings Article | 27 February 2015 Paper

Bringing mirrors to rest: grating concepts for ultra-precise interferometry

Stefanie Kroker, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 9372, 93720F (2015) https://doi.org/10.1117/12.2081446

KEYWORDS: Reflectivity, Mirrors, Diffraction gratings, Reflectors, Silicon, Metrology, Modulation, Transmittance, Interferometers, Diffraction

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Proceedings Article | 19 February 2014 Paper

Investigation on the angular dependent reflectance of coupled high-contrast gratings

Stefanie Kroker, Thomas Käsebier, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 8995, 89950B (2014) https://doi.org/10.1117/12.2039711

KEYWORDS: Reflectivity, Silicon, Reflectors, Optical components, Silica, Refractive index, Tolerancing, Light wave propagation, Resonators, Fabry–Perot interferometers

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Proceedings Article | 15 March 2013 Paper

Asymmetric direction selective filter elements based on high-contrast gratings

Stefan Steiner, Stefanie Kroker, Thomas Käsebier, Daniel Voigt, Jörg Fuchs, Frank Fuchs, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 8633, 86330Z (2013) https://doi.org/10.1117/12.2003930

KEYWORDS: Refractive index, Silicon, Optical filters, Diffraction gratings, Picosecond phenomena, Optical design, Diffraction, Silica, Binary data, Semiconductors

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Proceedings Article | 15 March 2013 Paper

High contrast gratings for high-precision metrology

Stefanie Kroker, Stefan Steiner, Thomas Käsebier, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 8633, 86330M (2013) https://doi.org/10.1117/12.2006074

KEYWORDS: Reflectivity, Silicon, Light scattering, Mirrors, Crystals, Metrology, Optical coatings, Optical components, Beam splitters, Diffraction gratings

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Proceedings Article | 23 February 2012 Paper

Tuning the reflectivity of high-contrast gratings based on silicon and silica by means of wet etching with hydrofluoric acid

Tassilo Jacobitz, Stefanie Kroker, Thomas Käsebier, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 8270, 82700U (2012) https://doi.org/10.1117/12.908240

KEYWORDS: Etching, Silica, Reflectivity, Silicon, Tolerancing, Wet etching, Ions, Oxides, HF etching, Thin films

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Proceedings Article | 23 February 2012 Paper

Diffractive optical elements based on subwavelength high-contrast gratings

Stefanie Kroker, Thomas Käsebier, Thomas Weber, Stefan Steiner, Frank Fuchs, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 8270, 82700P (2012) https://doi.org/10.1117/12.908145

KEYWORDS: Reflectivity, Silicon, Tolerancing, Silica, Modulation, Reflectors, Polarization, Optical components, Diffractive optical elements, Diffraction gratings

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Proceedings Article | 23 February 2012 Paper

High frequency binary amorphous silicon grating working as wire grid polarizer for UV applications

Thomas Weber, Thomas Käsebier, Stefanie Kroker, Ernst-Bernhard Kley, Andreas Tünnermann

Proceedings Volume 8270, 82700F (2012) https://doi.org/10.1117/12.906618

KEYWORDS: Polarizers, Silicon, Amorphous silicon, Ultraviolet radiation, Diffraction gratings, Refractive index, Optical testing, Etching, Optical properties, Mineralogy

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