Publication

of Prof. Uwe D. Zeitner

33 Publikationen filtern

Die Publikationen filtern

Highlighted authors are members of the University of Jena.

  1. Fabrication of shallow EUV gratings on silicon by irradiation with helium ions

    Year of publicationPublished in:Nanotechnology J. Kaufmann, R. Ciesielski, K. Freiberg, M. Walther, A. Fernández Herrero, S. Lippmann, V. Soltwisch, T. Siefke, U. Zeitner
    To accurately achieve structure height differences in the range of single digit nanometres is of great importance for the fabrication of diffraction gratings for the extreme ultraviolet range (EUV). Here, structuring of silicon irradiated through a mask by a broad beam of helium ions with an energy of 30 keV was investigated as an alternative to conventional etching, which offers only limited controllability for shallow structures due to the higher rate of material removal. Utilising a broad ion beam allows for quick and cost effective fabrication. Ion fluence of the irradiations was varied in the range of 10¹⁶ ... 10¹⁷ ions · cm⁻². This enabled a fine tuning of structure height in the range of 1.00 ± 0.05 to 20 ± 1 nm, which is suitable for shallow gratings used in EUV applications. According to transmission electron microscopy investigations the observed structure shape is attributed to the formation of point defects and bubbles/cavities within the silicon. Diffraction capabilities of fabricated elements are experimentally shown at the SX700 beamline of BESSY II. Rigorous Maxwell solver simulation based on the finite-element method and rigorous coupled wave analysis are utilised to describe the experimental obtained diffraction pattern.
    University Bibliography Jena:
    fsu_mods_00023928External link

  2. Fabrication of low-loss lithium niobate on insulator waveguides on the wafer scale [Invited]

    Year of publicationPublished in:Optical Materials Express M. Younesi, T. Kasebier, I. Elmanov, Y. Li, P. Kumar, R. Geiss, T. Siefke, F. Eilenberger, F. Setzpfandt, U. Zeitner, T. Pertsch
    We report on the wafer scale fabrication of single-mode low-loss lithium niobate on insulator waveguides utilizing a chemically amplified resist and an optimized dry etching method. The fabricated single-mode waveguides are free of residuals and re-deposition, with measured losses for straight waveguides around 2 dB/m (0.02 dB/cm). We present a method offering advantages for large-scale production mainly due to its cost-effectiveness and faster writing time. This work holds promise for advancing integrated photonics and optical communication technologies.
    University Bibliography Jena:
    fsu_mods_00020928External link

  3. Subwellenlängenstrukturen zur Erzeugung allgemeiner Phasenfunktionen

    Year of publication S. Linß
    Data transmission through optical fibers, lithographic production of semiconductor components, and sensors for autonomous driving are just a few examples for optical technologies in modern societies. The usage of diffractive optical elements (DOEs) offers possibilities for almost arbitrary manipulation of light within small available spaces. One popular approach is the use of metamaterials, which can have properties that are impossible for classical materials. Here, mainly effective-index structures of dielectric materials have been considered. Computer-generated holograms (CGHs), a special type of DOEs, can be used to generate almost arbitrary intensity distributions by their diffraction pattern. The simulation of light propagation through DOEs can be quite challenging. A rigorous simulation of the entire element is often too difficult due to the enormous computational requirements. The aim of this work is to overcome the limitations of established algorithms. For this purpose, new methods for the optical simulation of general DOEs have been developed: On the one hand, the use of suitable approximations allows a significant reduction of the computational effort to solve Maxwell's equations. On the other hand, physical simulations can be bypassed by machine learning to predict the optical function. In addition, the application of the new methods to design and optimization tasks is demonstrated. The presented methods can be used to optimize a variety of DOEs, for example metalenses or beamsplitters with high numerical aperture. In particular, the design of pattern generators for three-dimensional measurement of objects, face recognition, or camera calibration are promising application areas.
    University Bibliography Jena:
    fsu_mods_00014288External link

  4. Mid-infrared dielectric laser acceleration in a silicon dual pillar structure

    Year of publicationPublished in:Optics Express L. Brückner, T. Chlouba, Y. Morimoto, N. Schönenberger, T. Shibuya, T. Siefke, U. Zeitner, P. Hommelhoff
    Dielectric laser accelerators use near-infrared laser pulses to accelerate electrons at dielectric structures. Driving these devices with mid-infrared light should result in relaxed requirements on the electron beam, easier fabrication, higher damage threshold, and thus higher acceleration gradients. In this paper, we demonstrate dielectric laser acceleration of electrons driven with 10 µm light in a silicon dual pillar structure. We observe the acceleration of 27 keV electrons by 1.4 keV, corresponding to a 93 MeV/m acceleration gradient. The damage threshold of the structures of 3.3 ± 0.6 GV/m peak field is significantly higher than for near-infrared accelerators. The dual pillar acceleration structure itself even survived 5.2 ± 0.9 GV/m, the highest field strength we could achieve with the current system. This together with the larger structure acceptance bodes well for future dielectric laser accelerators driven with mid-infrared light.
    University Bibliography Jena:
    fsu_mods_00015789External link

  5. Miniaturized fluorescence measurement system with novel dichroic beam splitter cubes with 3 by 3 by 3 cubic millimeters and special optical direction-selective filters

    Year of publicationPublished in:Optical Design and Engineering IX R. Müller, T. Siefke, U. Zeitner, K. Neckermann, M. Hintz, B. Ploss, M. Lappschies
    University Bibliography Jena:
    fsu_mods_00016232External link

  6. Direct bonding of wafers on non-planar optical substrates and bonding energy measurement via the novel κ-method

    Year of publication P. Birckigt
    In this thesis, the novel concept of direct bonding of wafers on non-planar substrates – in particular, convex cylindrical and convex spherical substrates – is explored, challenging the paradigm that direct bonding requires both surfaces to be highly planar. The motivation stems from the desire to combine advanced diffractive optical elements (DOEs) – which can lithographically only be written into planar substrates – with optical lenses in order to obtain new optical functionalities. As part of this effort, mathematical models to predict complete area stable contacting success are developed and the mechanical stressed bonding interface is investigated through time-resolved contact front propagation experiments. Also, a novel, highly accurate method for measuring the bonding energy in non-planar interfaces is introduced. It was found that direct bonding success can be predicted for a large range of use cases as a function of the wafer’s and the substrate’s geometry. Also, it was discovered that the bonding energy of a mechanically stressed interface stabilizes at a consistent level regardless of the surface waviness. A reaction kinetics model for explaining this phenomenon has been proposed. A demonstrator combining an optical lens and a DOE is manufactured to showcase the potential of direct bonding of wafers on non-planar substrates for the field of advanced optics.
    University Bibliography Jena:
    fsu_mods_00013523External link

  8. Novel phase masks with overlapping regions to fabricate fiber Bragg gratings for filtering sky emission lines

    Year of publicationPublished in:Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VI X. Luo, A. Rahman, K. Madhav, T. Siefke, R. Krämer, D. Richter, U. Zeitner, S. Nolte, M. Roth
    University Bibliography Jena:
    fsu_mods_00017635External link

  9. Structured illumination ptychography and at-wavelength characterization with an EUV diffuser at 13.5 nm wavelength

    Year of publicationPublished in:Optics Express W. Eschen, C. Liu, M. Steinert, D. Penagos Molina, T. Siefke, U. Zeitner, J. Kasper, T. Pertsch, J. Limpert, J. Rothhardt, J. Kaspar
    Structured illumination is essential for high-performance ptychography. Especially in the extreme ultraviolet (EUV) range, where reflective optics are prevalent, the generation of structured beams is challenging and, so far, mostly amplitude-only masks have been used. In this study, we generate a highly structured beam using a phase-shifting diffuser optimized for 13.5 nm wavelength and apply this beam to EUV ptychography. This tailored illumination significantly enhances the quality and resolution of the ptychography reconstructions. In particular, when utilizing the full dynamics range of the detector, the resolution has been improved from 125 nm, when using an unstructured beam, to 34 nm. Further, ptychography enables the quantitative measurement of both the amplitude and phase of the EUV diffuser at 13.5 nm wavelength. This capability allows us to evaluate the influence of imperfections and contaminations on its “at wavelength” performance, paving the way for advanced EUV metrology applications and highlighting its importance for future developments in nanolithography and related fields.
    University Bibliography Jena:
    fsu_mods_00010443External link

  10. Wafer-scale nanofabrication of sub-5 » nm gaps in plasmonic metasurfaces

    Year of publicationPublished in:Nanophotonics J. Gour, S. Beer, P. Paul, A. Alberucci, M. Steinert, A. Szeghalmi, T. Siefke, U. Peschel, S. Nolte, U. Zeitner
    In the rapidly evolving field of plasmonic metasurfaces, achieving homogeneous, reliable, and reproducible fabrication of sub-5 » nm dielectric nanogaps is a significant challenge. This article presents an advanced fabrication technology that addresses this issue, capable of realizing uniform and reliable vertical nanogap metasurfaces on a whole wafer of 100 » mm diameter. By leveraging fast patterning techniques, such as variable-shaped and character projection electron beam lithography (EBL), along with atomic layer deposition (ALD) for defining a few nanometer gaps with sub-nanometer precision, we have developed a flexible nanofabrication technology to achieve gaps as narrow as 2 » nm in plasmonic nanoantennas. The quality of our structures is experimentally demonstrated by the observation of resonant localized and collective modes corresponding to the lattice, with Q-factors reaching up to 165. Our technological process opens up new and exciting opportunities to fabricate macroscopic devices harnessing the strong enhancement of light-matter interaction at the single nanometer scale.
    University Bibliography Jena:
    fsu_mods_00016862External link

  11. Design of computer-generated holograms based on semi-rigorous simulations of sub-wavelength structures

    Year of publicationPublished in:Optics Express S. Lins, U. Zeitner
    Conventional design methods for computer-generated holograms often rely on the scalar diffraction theory because the calculation effort of rigorous simulations is too high. But for sub-wavelength lateral feature sizes or large deflection angles, the performance of realized elements will show distinct deviations from the expected scalar behavior. We propose a new design method that overcomes this issue by incorporating high-speed semi-rigorous simulation techniques that allow the modeling of light propagation at an accuracy close to the rigorous methods. This includes an approach to solve the inverse problem of calculating a geometric structure that is able to form a certain physical field distribution.
    University Bibliography Jena:
    fsu_mods_00004236External link

  12. Measurement of the bonding energy via non-planar direct bonding

    Year of publicationPublished in:Journal of applied physics P. Birckigt, C. Rothhardt, G. Harnisch, S. Risse, U. Zeitner
    An accurate measurement of the bonding energy of an interface is important in many areas of applied research. We present a novel method for measuring the bonding energy, which is based on the principle of non-planar direct bonding, i.e., direct bonding of originally planar wafers onto non-planar substrates. We discuss in detail the advantages and disadvantages compared to the commonly used double cantilever beam method. To demonstrate the practical relevance, by using the example of glass wafers, the evolution of the bonding energy during different de-bonding steps is investigated, focusing on how the surface shape variations and the surface roughness affects water stress corrosion. We find that the bonding energy in the corroded state is not affected by the original surface shape variations and mid-spatial frequency range roughness, anymore. A molecular mechanism to explain this phenomenon is proposed.
    University Bibliography Jena:
    fsu_mods_00005405External link
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