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Alexander Lambertz

Publications and source records attributed to Alexander Lambertz.

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Large-Area Deterministic Stamping of 2D Materials on Arbitrarily Patterned Surfaces

2D materials and their monolayers have attracted widespread interest by virtue of their unique electronic and optical properties. In addition to their remarkable physical characteristics, their atomically thin nature enables their integration in ultra-compact photonic and electronic devices, with potential for dynamic tunability via strain, charge carrier modulation or heterostructure engineering. While early research relied on micrometer-scale mechanically exfoliated flakes, recent advances, particularly gold-assisted exfoliation of transition metal dichalcogenides (TMDCs), have enabled the preparation of high-quality, large-area monolayers, opening new opportunities for scalable device integration. For the field of nanophotonics in particular, the ability to transfer large-area 2D materials onto both flat and patterned substrates is essential for the development of functional devices. However, existing transfer techniques are often limited in scalability, and compatibility with structured surfaces. Here, we present a versatile and reliable transfer method of large-area monolayers and hBN/monolayer heterostructures onto both flat and nanostructured substrates. Our approach, based on the physical properties of low-density polyethylene, preserves the intrinsic optical quality of the materials and is compatible with a variety of device architectures. We demonstrate its applicability by fabricating devices that modulate the photoluminescence of TMDC monolayers through the manipulation of the photonic environment, strain or electrical gating. We further demonstrate the fabrication of van der Waals heterostructures using the same method. By enabling clean transfer of a wide range of monolayers and heterostructures, this technique offers a practical pathway for the development of next-generation optoelectronic platforms with improved functionality, scalability, and tunability.

cond-mat.mes-hall

Blob Detection for Photonic Metasurface Designing: Angular and Spectral Control of Scattered Light

Metasurfaces with precise spectral and angular control of light scattering are of growing interest for photonic applications requiring advanced photon management. Correlated disorder emerged as a promising route for angular control of light scattering, but most design approaches are computationally expensive or do not allow spectral tunability. Here, we introduce a reverse-engineering design approach for correlated-disordered metasurfaces based on tailoring the Fourier space and blob detection to create point distributions that are later "decorated" with individually designed nano-resonators or meta-atoms to tune the optical response for the desired functionality. We validate the control of the angular scattering by fabricating ensembles of Au nanopillars following our design and characterizing their angular scattering with Fourier microscopy. Using finite-difference time-domain simulations, we demonstrate how the choice of decorative unit tunes the spectral response, showcasing individual and independent control over light scattering in angular and spectral terms. Lastly, we expand the limits of our versatile approach by combining multiple metasurfaces in one, effectively adding their individual scattering characteristics. As such, we can address spectral and angular ranges independently, yielding a high degree of control of the scattering response.

physics.optics