Publications list of the department Theoretical Physics 2

Frau Prof. Dr. Kathy Lüdge

latest publications:
L. Jaurigue, E. Robertson, J. Wolters, K. Lüdge
Reservoir Computing with Delayed Input for Fast and Easy Optimisation
Entropy 2021, 23(12), 1560
A. Roos, S. Meinecke, K. Lüdge,
Stabilizing Nanolasers via Polarization Lifetime Tuning Sci. Rep. 11, 18558 ( 2021 )

F. Köster, B. Lingnau, A. Krimlowski, P. Hövel, K. Lüdge:
Collective coherence resonance in networks of optical neurons Phys. Status Solidi B 2021, 2100345 (2021)

J. Hausen, B. Herzog, A. Nelde, S. Meinecke, N. Owschimikow, K. Lüdge:
Feedback induced locking in semiconductor lasers with strong amplitude-phase coupling Phys. Rev. A 103, 043511 (2021)

S. Meinecke, K. Lüdge:
Efficient timing jitter simulation for passively mode-locked semiconductor lasers App. Phys. Lett. 118, 011104 (2021)

F. Köster, D. Ehlert, K. Lüdge:
Limitations of the recall capabilities in delay based reservoir computing systems Cogn. Comput. 2020, (2020)

list of publications


Publications list Theoretical Physics 2

Anzahl der Treffer: 208
Erstellt: Fri, 27 May 2022 23:09:27 +0200 in 0.0505 sec

Hülser, Tobias; Köster, Felix; Jaurigue, Lina; Lüdge, Kathy;
Role of delay-times in delay-based photonic reservoir computing. - In: Optical materials express, ISSN 2159-3930, Bd. 12 (2022), 3, S. 1214-1231

Delay-based reservoir computing has gained a lot of attention due to the relative simplicity with which this concept can be implemented in hardware. However, unnecessary constraints are commonly placed on the relationship between the delay-time and the input clock-cycle, which can have a detrimental effect on the performance. We review the existing literature on this subject and introduce the concept of delay-based reservoir computing in a manner that demonstrates that no predefined relationship between the delay-time and the input clock-cycle is required for this computing concept to work. Choosing the delay-times independent of the input clock-cycle, one gains an important degree of freedom. Consequently, we discuss ways to improve the computing performance of a reservoir formed by delay-coupled oscillators and show the impact of delay-time tuning in such systems.
Jaurigue, Lina; Lüdge, Kathy;
Connecting reservoir computing with statistical forecasting and deep neural networks. - In: Nature Communications, ISSN 2041-1723, Bd. 13 (2022), 227, insges. 3 S.

Among the existing machine learning frameworks, reservoir computing demonstrates fast and low-cost training, and its suitability for implementation in various physical systems. This Comment reports on how aspects of reservoir computing can be applied to classical forecasting methods to accelerate the learning process, and highlights a new approach that makes the hardware implementation of traditional machine learning algorithms practicable in electronic and photonic systems.
Kreismann, Jakob;
Three-dimensional optical microcavities: from geometric phases to tailored far-field emission. - Ilmenau : Universitätsbibliothek, 2021. - 1 Online-Ressource (iii, 204 Seiten)
Technische Universität Ilmenau, Dissertation 2021

Diese Arbeit behandelt dreidimensionale optische Mikrokavitäten in Bezug auf ihre Resonanzmoden. Die optischen Mikrokavitäten reichen dabei von Möbiusband-Kavitäten über zylindrische und kegelförmige Ringkavitäten sowie kegelförmige Tube-Kavitäten bis hin zu Arrays von Lima¸con-Kavitäten. Im ersten Teil werden flüstergalerieartige Moden von dielektrischen Möbiusband-Kavitäten mit Hilfe von FDTD-Simulationen untersucht. Die Topologie des Möbiusbands erlaubt die Entstehung einer geometrischen Phase und zwar der Pancharatnam-Phase. Darauf aufbauend wird untersucht, wie die Pancharatnam-Phase durch Verkürzung der Länge des verdrehten Anteils oder durch Erhöhung der Dicke des Möbiusbands manipuliert werden kann. Dabei untersuchen wir, wie die Polarisation und die Fernfelder der flüstergalerieartigen Moden beeinflusst werden. Außerdem wird die Nonagon-Möbiusband-Kavität - eine Möbiusband-Kavität mit Querschnittsform dreifacher Rotationssymmetrie - eingeführt, die ebenfalls eine Manipulation der Pancharatnam-Phase ermöglicht. Im zweiten Teil werden propagierende flüstergalerieartige Moden in zylindrischen Ringkavitäten, konischen Ringkavitäten und konischen Tube-Kavitäten mittels FDTD-Simulationen und vektorieller Beugungstheorie untersucht. Der propagierende Charakter der Moden ermöglicht die sogenannte Spin-Richtungs-Wechselwirkung des Lichts. Darauf aufbauend wird untersucht, wie die Fernfeldpolarisation durch die axiale Morphologie der flüstergalerieartigen Moden und durch geometrische Eigenschaften der Kavitäten wie die Öffnungswinkel von konischen Ring- und Tube-Kavitäten beeinflusst wird. Mit Hilfe vektorieller Beugungstheorie wird ein qualitativer Zusammenhang zwischen den lokalen Eigenschaften der Moden im Inneren der Kavität und der Fernfeldpolarisation beschrieben. Dabei wird die Rolle von Beugung und Präzession des elektrischen Feldvektors um die Kavitätenachse diskutiert. Es wird gezeigt, dass elliptische und zirkulare Polarisationszustände im Fernfeld unmittelbar durch propagierende flüstergalerieartige Moden auftreten, auch ohne inhomogenes oder anisotropes Kavitätenmaterial. Im dritten Teil wird die Fernfeldabstrahlung von linearen Arrays bestehend aus Lima¸con-Kavitäten mithilfe von FDTD-Simulationen untersucht. Während das Fernfeld einer einzelnen Lima¸con-Kavität gerichtete Emission aufweist, wird untersucht, wie sich diese gerichtete Emission in Abhängigkeit der Arrayeigenschaften wie dem Abstand zwischen den Kavitäten und der Anzahl der Kavitäten ändert. Es wird gezeigt, dass die Abstrahlung des Arrays entweder weiter verstärkt (Superdirektionalität) oder sogar umgekehrt Kavitäten werden kann (Richtungsumkehr).
Jaurigue, Lina; Robertson, Elizabeth; Wolters, Janik; Lüdge, Kathy;
Reservoir computing with delayed input for fast and easy optimisation. - In: Entropy, ISSN 1099-4300, Bd. 23 (2021), 12, 1560, S. 1-13

Reservoir computing is a machine learning method that solves tasks using the response of a dynamical system to a certain input. As the training scheme only involves optimising the weights of the responses of the dynamical system, this method is particularly suited for hardware implementation. Furthermore, the inherent memory of dynamical systems which are suitable for use as reservoirs mean that this method has the potential to perform well on time series prediction tasks, as well as other tasks with time dependence. However, reservoir computing still requires extensive task-dependent parameter optimisation in order to achieve good performance. We demonstrate that by including a time-delayed version of the input for various time series prediction tasks, good performance can be achieved with an unoptimised reservoir. Furthermore, we show that by including the appropriate time-delayed input, one unaltered reservoir can perform well on six different time series prediction tasks at a very low computational expense. Our approach is of particular relevance to hardware implemented reservoirs, as one does not necessarily have access to pertinent optimisation parameters in physical systems but the inclusion of an additional input is generally possible.
Bosch, Martí; Behrens, Arne; Sinzinger, Stefan; Hentschel, Martina;
Husimi functions for coupled optical resonators. - In: Journal of the Optical Society of America, ISSN 1520-8532, Bd. 38 (2021), 4, S. 573-578

Phase-space analysis has been widely used in the past for the study of optical resonant systems. While it is usually employed to analyze the far-field behavior of resonant systems, we focus here on its applicability to coupling problems. By looking at the phase-space description of both the resonant mode and the exciting source, it is possible to understand the coupling mechanisms as well as to gain insights and approximate the coupling behavior with reduced computational effort. In this work, we develop the framework for this idea and apply it to a system of an asymmetric dielectric resonator coupled to a waveguide.
Bosch, Martí; Behrens, Arne; Sinzinger, Stefan; Hentschel, Martina;
Optische Systeme im Phasenraumbild. - In: DGaO-Proceedings, ISSN 1614-8436, Bd. 121 (2020), B29, insges. 2 S.
Kreismann, Jakob; Hentschel, Martina;
Spin-orbit interaction of light in three-dimensional microcavities. - In: Physical review, ISSN 2469-9934, Bd. 102 (2020), 4, S. 043524

We investigate the spin-orbit coupling of light in three-dimensional cylindrical and tubelike whispering gallery mode resonators. We show that its origin is the transverse confinement of light in the resonator walls, even in the absence of inhomogeneities or anisotropies. The spin-orbit interaction results in elliptical far-field polarization (spin) states and causes spatial separation of polarization handedness in the far field. The ellipticity and spatial separation are enhanced for whispering gallery modes with higher excitation numbers along the resonator height. We analyze the asymmetry of the ellipticity and the tilt of the polarization orientation in the far field of conelike microcavities. Furthermore, we find a direct relationship between the tilt of the polarization orientation in the far field and the local inclination of the resonator wall. Our findings are based on finite-difference time-domain simulations and are supported by three-dimensional diffraction theory.
Heyder, Florian; Schumacher, Jörg; Hentschel, Martina;
Moist Rayleigh-Bérnard Convection in conditionally unstable environments. - In: DPG-Frühjahrstagung (DPG Spring Meeting) of the Condensed Matter Section (SKM) together with the DPG Division Environmental Physics and the Working Groups Accelerator Physics; Equal Opportunities; Energy; Industry and Business; Physics, Modern IT and Artificial Intelligence, Young DPG, (2020), DY 16.3

Behrens, Arne; Bosch, Martí; Feßer, Patrick; Hentschel, Martina; Sinzinger, Stefan;
Fabrication and characterization of deformed microdisk cavities in silicon dioxide with high Q-factor. - In: Applied optics, ISSN 2155-3165, Bd. 59 (2020), 26, S. 7893-7899

We demonstrate the excitation and characterization of whispering gallery modes in a deformed optical microcavity. To fabricate deformed microdisk microresonators we established a fabrication process relying on dry plasma etching tools for many degrees of freedom and a shape-accurate morphology. This approach allowed us to fabricate resonators of different sizes with a controlled sidewall angle and underetching in large quantities with reproducible properties such as a surface roughness RQ ≤ 2nm. The excitation and characterization of these modes were achieved by using a state-of-the-art tapered fiber coupling setup with a narrow linewidth tunable laser source. The conducted measurements in shortegg resonators showed at least two modes within a spectral range of about 237 pm. The highest Q-factors measured were in the range of 105. Wave optical eigenmode and frequency domain simulations were conducted that could partially reproduce the observed behavior and therefore allow us to compare the experimental results.
Kim, Jaewon; Ryu, Jung-Wan;
Splitting and combining of exceptional points. - In: DPG-Frühjahrstagung (DPG Spring Meeting) of the Condensed Matter Section (SKM) together with the DPG Division Environmental Physics and the Working Groups Accelerator Physics; Equal Opportunities; Energy; Industry and Business; Physics, Modern IT and Artificial Intelligence, Young DPG, (2020), KFM 7.5