Universität Stuttgart
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Item Open Access Direct electron beam patterning of electro-optically active PEDOT:PSS(2024) Doshi, Siddharth; Ludescher, Dominik; Karst, Julian; Floess, Moritz; Carlström, Johan; Li, Bohan; Mintz Hemed, Nofar; Duh, Yi-Shiou; Melosh, Nicholas A.; Hentschel, Mario; Brongersma, Mark; Giessen, HaraldThe optical and electronic tunability of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has enabled emerging applications as diverse as bioelectronics, flexible electronics, and micro- and nano-photonics. High-resolution spatial patterning of PEDOT:PSS opens up opportunities for novel active devices in a range of fields. However, typical lithographic processes require tedious indirect patterning and dry etch processes, while solution-processing methods such as ink-jet printing have limited spatial resolution. Here, we report a method for direct write nano-patterning of commercially available PEDOT:PSS through electron-beam induced solubility modulation. The written structures are water stable and maintain the conductivity as well as electrochemical and optical properties of PEDOT:PSS, highlighting the broad utility of our method. We demonstrate the potential of our strategy by preparing prototypical nano-wire structures with feature sizes down to 250 nm, an order of magnitude finer than previously reported direct write methods, opening the possibility of writing chip-scale microelectronic and optical devices. We finally use the high-resolution writing capabilities to fabricate electrically-switchable optical diffraction gratings. We show active switching in this archetypal system with >95 % contrast at CMOS-compatible voltages of +2 V and -3 V, offering a route towards highly-miniaturized dynamic optoelectronic devices.Item Open Access Tailored nanocomposites for 3D printed micro-optics(2020) Weber, Ksenia; Werdehausen, Daniel; König, Peter; Thiele, Simon; Schmid, Michael; Decker, Manuel; Oliveira, Peter William de; Herkommer, Alois; Giessen, HaraldItem Open Access Phonon-polaritonic skyrmions : transition from bubble- to Néel-type(2026) Mangold, Florian; Baù, Enrico; Nan, Lin; Schwab, Julian; Gölz, Thorsten; Mancini, Andrea; Frank, Bettina; Tittl, Andreas; Giessen, HaraldOptical skyrmions are members of the emerging topological branch of solid-state physics and photonics, allowing for control over topological light textures through light-matter interactions. However, in nanophotonics their practical application has been severely limited by high inherent losses in plasmonic materials, resulting in the lack of tunability between different topological properties. Here, we utilize the strong dispersion of silicon carbide thin films to realize highly confined surface phonon-polariton skyrmion lattices, which we image via near-field microscopy. We experimentally demonstrate topological tuning between bubble- and Néel-type skyrmions, a unique advantage that polar dielectrics offer over most existing approaches. Changing the excitation wavelength by only 10% switches the skyrmion type, revealed by examination of the skyrmion number density contrast. Analysis of domain wall size and steepness in analogy to magnetic materials also confirms this transition. Our results are a starting point to investigate other topological features in phononic systems such as merons, skyrmion bags, and other complex structured light fields. Furthermore, strong light-matter hybridization and nonlinear effects owing to anharmonicity of the phonons may be observed in the future, possibly leading towards the discovery of polaritonic skyrmion-skyrmion interactions and hence applications in topology-based information processing.Item Open Access Effects of high-power laser radiation on polymers for 3D printing micro-optics(2023) Klein, Sebastian; Ruchka, Pavel; Klumpp, Thomas; Bartels, Nils; Steinle, Tobias; Giessen, HaraldItem Open Access Continuous-wave injection-seeded multipass OPA for direct 1 W, 76 MHz, sub-50 fs pulse generation at 1.5-1.7 μm(2025) Kadriu, Florent; Thannheimer, Johann; Flad, Philipp; Steinle, Tobias; Giessen, HaraldItem Open Access Electronically tunable fiber-feedback optical parametric oscillator with intracavity echelle grating stretcher(2025) Kadriu, Florent; Kuppel, Sandro; Harteker, Michael; Hirsch, Felix; Steinle, Tobias; Giessen, HaraldItem Open Access Inverse design of all-dielectric metasurfaces with accidental bound states in the continuum(2023) Gladyshev, Sergei; Karamanos, Theodosios D.; Kuhn, Lina; Beutel, Dominik; Weiss, Thomas; Rockstuhl, Carsten; Bogdanov, AndreyMetasurfaces with bound states in the continuum (BICs) have proven to be a powerful platform for drastically enhancing light–matter interactions, improving biosensing, and precisely manipulating near- and far-fields. However, engineering metasurfaces to provide an on-demand spectral and angular position for a BIC remains a prime challenge. A conventional solution involves a fine adjustment of geometrical parameters, requiring multiple time-consuming calculations. In this work, to circumvent such tedious processes, we develop a physics-inspired, inverse design method on all-dielectric metasurfaces for an on-demand spectral and angular position of a BIC. Our suggested method predicts the core–shell particles that constitute the unit cell of the metasurface, while considering practical limitations on geometry and available materials. Our method is based on a smart combination of a semi-analytical solution, for predicting the required dipolar Mie coefficients of the meta-atom, and a machine learning algorithm, for finding a practical design of the meta-atom that provides these Mie coefficients. Although our approach is exemplified in designing a metasurface sustaining a BIC, it can, also, be applied to many more objective functions. With that, we pave the way toward a general framework for the inverse design of metasurfaces in specific and nanophotonic structures in general.Item Open Access From two‐photon grayscale lithography to scalable replication : enabling complex aspherical micro‐optics for mass production(2025) Wagner, Stefan; Siegle, Leander; Haeusler, Stephan; Flad, Philipp; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Giessen, HaraldThe evolution of complex micro‐optics from prototyping to scalable manufacturing is a key challenge for modern imaging, sensing, and photonic systems. Two‐photon polymerization grayscale lithography (2GL) revolutionized the fabrication of micro‐optics by combining aspherical lenses with micro‐features enabling performance increases, weight reduction, aberration correction, and beam shaping. Its scalability for mass production, however, remains a key limitation. In this study, the replication and integration of 3D printed optics are demonstrated through electroplating and injection molding processes, enabling high‐volume production without sacrificing precision. Advancements in replicating complex micro‐optics fabricated via 2GL are presented by designing and 3D printing a diffractive, aspherical micro‐lens array. In relation to their size, these optics are almost impossible to produce with common techniques such as precision turning. The topography, beam profiles, and imaging quality of the 3D printed master are compared to the replicated lens array. By combining 2GL 3D printing and injection molding, micro‐optical mass production of arbitrary geometries is enabled. It is highlighted how this approach unlocks new opportunities for scalable production, addressing disparities between rapid prototyping and industrial manufacturing of micro‐optics.Item Open Access Diffractive microoptics in porous silicon oxide by grayscale lithography(2024) Siegle, Leander; Xie, Dajie; Richards, Corey A.; Braun, Paul V.; Giessen, HaraldItem Open Access Mass-producible micro-optical elements by injection compression molding and focused ion beam structured titanium molding tools(2020) Ristok, Simon; Roeder, Marcel; Thiele, Simon; Hentschel, Mario; Guenther, Thomas; Zimmermann, André; Herkommer, Alois; Giessen, Harald