TY - CONF AB - This paper experimentally investigates and interprets the e®ects of noise and non- linearity in a silicon photonic optical test structure. For the analysis di®erent optoelectronic phase noise measurement techniques are used. Our tests focuses on the performance of integrated opti- cal test structures using femtosecond pulses in the 1550nm spectral range. A primary objective is to understand the behaviour of silicon photonic waveguides that can be further employed in the implementation of an optoelectronic phase-locked loop (OEPLL) in silicon photonics technology. A comparison of our results, as well as a discussion on the di®erent optoelectronic phase noise measurement techniques are presented. Our ¯ndings provide insights that can be leveraged to optimize the design and performance of ultra-low phase noise on-chip OEPLL systems locking to mode-locked laser (MLL) signals. In the future such systems can be essential for advanced communication and sensing applications. AU - Surendranath Shroff, Vijayalakshmi AU - Kress, Christian AU - Bahmanian, Meysam AU - Scheytt, J. Christoph ID - 47521 T2 - 2023 PhotonIcs & Electromagnetics Research Symposium (PIERS), TI - Analysis of Phase Noise in Waveguide-integrated Optical Test Structures in Silicon Photonics ER - TY - JOUR AU - Kürpick, Christian AU - Rasor, Anja AU - Scholtysik, Michel AU - Kühn, Arno AU - Koldewey, Christian AU - Dumitrescu, Roman ID - 47420 JF - Procedia CIRP KW - General Medicine SN - 2212-8271 TI - An Integrative View of the Transformations towards Sustainability and Digitalization: The Case for a Dual Transformation VL - 119 ER - TY - JOUR AU - Zhai, Xiaokun AU - Ma, Xuekai AU - Gao, Ying AU - Xing, Chunzi AU - Gao, Meini AU - Dai, Haitao AU - Wang, Xiao AU - Pan, Anlian AU - Schumacher, Stefan AU - Gao, Tingge ID - 40274 IS - 13 JF - Physical Review Letters TI - Electrically controlling vortices in a neutral exciton polariton condensate at room temperature VL - 131 ER - TY - GEN AU - Sehlmeyer, Birte AU - Kampmann, Rebecca AU - Scheidemann, Claus AU - Hemsel, Tobias AU - Getzlaff, Mathias ID - 47234 T2 - Frühjahrstagung 2023, Sektion Kondensierte Materie (SKM) TI - Burst Mode of Ultrasonic Resonant Oscillations for Stimulation and Destruction of Tumor Cells ER - TY - GEN AU - Kampmann, Rebecca AU - Sehlmeyer, Birte AU - Scheidemann, Claus AU - Hemsel, Tobias AU - Getzlaff, Mathias ID - 47235 T2 - Frühjahrstagung 2023, Sektion Kondensierte Marterie (SKM) TI - Burst Mode Characteristics of an Ultrasonic Transducer for Treatment of Cancer Cells ER - TY - GEN AB - In planar microcavities, the transverse-electric and transverse-magnetic (TE-TM) mode splitting of cavity photons arises due to their different penetration into the Bragg mirrors and can result in optical spin-orbit coupling (SOC). In this work, we find that in a liquid crystal (LC) microcavity filled with perovskite microplates, the pronounced TE-TM splitting gives rise to a strong SOC that leads to the spatial instability of microcavity polariton condensates under single-shot excitation. Spatially varying hole burning and mode competition occurs between polarization components leading to different condensate profiles from shot to shot. The single-shot polariton condensates become stable when the SOC vanishes as the TE and TM modes are spectrally well separated from each other, which can be achieved by application of an electric field to our LC microcavity with electrically tunable anisotropy. Our findings are well reproduced and traced back to their physical origin by our detailed numerical simulations. With the electrical manipulation our work reveals how the shot-to-shot spatial instability of spatial polariton profiles can be engineered in anisotropic microcavities at room temperature, which will benefit the development of stable polariton-based optoeletronic and light-emitting devices. AU - Gao, Ying AU - Ma, Xuekai AU - Zhai, Xiaokun AU - Xing, Chunzi AU - Gao, Meini AU - Dai, Haitao AU - Wu, Hao AU - Liu, Tong AU - Ren, Yuan AU - Wang, Xiao AU - Pan, Anlian AU - Hu, Wei AU - Schumacher, Stefan AU - Gao, Tingge ID - 47532 T2 - arXiv:2305.01368 TI - Single-shot spatial instability and electric control of polariton condensates at room temperature ER - TY - GEN AB - The control and active manipulation of spin-orbit coupling (SOC) in photonic systems is fundamental in the development of modern spin optics and topological photonic devices. Here, we demonstrate the control of an artificial Rashba-Dresselhaus (RD) SOC mediated by photochemical reactions in a microcavity filled with an organic single-crystal of photochromic phase-change character. Splitting of the circular polarization components of the optical modes induced by photonic RD SOC is observed experimentally in momentum space. By applying an ultraviolet light beam, we control the spatial molecular orientation through a photochemical reaction and with that we control the energies of the photonic modes. This way we realize a reversible conversion of spin-splitting of the optical modes with different energies, leading to an optically controlled switching between circularly and linearly polarized emission from our device. Our strategy of in situ and reversible engineering of SOC induced by a light field provides a promising approach to actively design and manipulate synthetic gauge fields towards future on-chip integration in photonics and topological photonic devices. AU - Liang, Qian AU - Ma, Xuekai AU - Ren, Jiahuan AU - Long, Teng AU - Gu, Chunling AU - An, Cunbin AU - Fu, Hongbing AU - Schumacher, Stefan AU - Liao, Qing ID - 47533 T2 - arXiv:2309.07652 TI - Photochemical reaction enabling the engineering of photonic spin-orbit coupling in organic-crystal optical microcavities ER - TY - GEN AB - Topological states have been widely investigated in different types of systems and lattices. In the present work, we report on topological edge states in double-wave (DW) chains, which can be described by a generalized Aubry-Andr\'e-Harper (AAH) model. For the specific system of a driven-dissipative exciton polariton system we show that in such potential chains, different types of edge states can form. For resonant optical excitation, we further find that the optical nonlinearity leads to a multistability of different edge states. This includes topologically protected edge states evolved directly from individual linear eigenstates as well as additional edge states that originate from nonlinearity-induced localization of bulk states. Extending the system into two dimensions (2D) by stacking horizontal DW chains in the vertical direction, we also create 2D multi-wave lattices. In such 2D lattices multiple Su-Schrieffer-Heeger (SSH) chains appear along the vertical direction. The combination of DW chains in the horizontal and SSH chains in the vertical direction then results in the formation of higher-order topological insulator corner states. AU - Schneider, Tobias AU - Gao, Wenlong AU - Zentgraf, Thomas AU - Schumacher, Stefan AU - Ma, Xuekai ID - 47531 T2 - arXiv:2303.12593 TI - Topological edge and corner states in coupled wave lattices in nonlinear polariton condensates ER - TY - GEN AB - Exceptional points (EPs) with their intriguing spectral topology have attracted considerable attention in a broad range of physical systems, with potential sensing applications driving much of the present research in this field. Here we theoretically demonstrate the realization of EPs in a system with significant nonlinearity, a non-equilibrium exciton-polariton condensate. With the possibility to control loss and gain and nonlinearity by optical means, this system allows for a comprehensive analysis of the interplay of nonlinearities (Kerr-type and saturable gain) and non-Hermiticity. Not only do we find that EPs can be intentionally shifted in parameter space by the saturable gain, we also observe intriguing rotations and intersections of Riemann surfaces, and find nonlinearity-enhanced sensing capabilities. Our results are quite general in nature and illustrate the potential of tailoring spectral topology and related phenomena in non-Hermitian systems by nonlinearity. AU - Wingenbach, Jan AU - Schumacher, Stefan AU - Ma, Xuekai ID - 47529 T2 - arXiv:2305.04855 TI - Tweaking Spectral Topology and Exceptional Points by Nonlinearity in Non-Hermitian Polariton Systems ER - TY - JOUR AB - AbstractEfforts to enhance sustainability in all areas of life are increasing worldwide. In the field of manufacturing technology, a wide variety of approaches are being used to improve both resource and energy efficiency. Efficiency as well as sustainability can be improved by creating a circular economy or through energy-efficient recycling processes. As part of the interdisciplinary research group "Light—Efficient—Mobile" investigations on the energy-efficient friction-induced recycling process have been carried out at the department of Forming and Machining Technology at Paderborn University. E.g. using the friction-induced recycling process, different formless solid aluminum materials can be direct recycled into semi-finished products in an energy-efficient manner. The results of investigations with regard to the influence of the geometrical shape and filling rate of the aluminum particles to be recycled as well as the rotational speed of the continuously rotating wheel are explained in this paper. In addition to the recycling of aluminum chips, aluminum particles like powders from the field of additive manufacturing are processed. Based on these results, the future potentials of solid-state recycling processes and their contribution to the circular economy are discussed. The main focus here is on future interdisciplinary research projects to achieve circularity in the manufacturing of user-individual semi-finished products as well as the possibility to selectively adjust the product properties with the continuous recycling process. AU - Borgert, Thomas AU - Milaege, Dennis AU - Schweizer, Swetlana AU - Homberg, Werner AU - Schaper, Mirko AU - Tröster, Thomas ID - 47536 IS - 6 JF - International Journal of Material Forming KW - General Materials Science SN - 1960-6206 TI - Potentials of a friction-induced recycling process to improve resource and energy efficiency in manufacturing technology VL - 16 ER -