Article
Engineering, Mechanical
Panagiotis Georgiou, Christos Tselios, Georgia Mourkioti, Charalampos Skokos, Dimitris Alexandropoulos
Summary: This study numerically investigates the chaotic dynamics of optically pumped quantum-dot spin vertically coupled surface emitting lasers, considering both ground state and excited state energy levels. The intensity dynamics of excited state and ground state transitions are studied through the elaboration of a spin-flip model, and it is found that although they exhibit similar nonlinear dynamics, they are weakly correlated, which can be utilized for implementing various functionalities.
NONLINEAR DYNAMICS
(2021)
Article
Mathematics, Interdisciplinary Applications
Zayneb Brari, Safya Belghith
Summary: This paper investigates the complex behavior and noise contamination issues in electroencephalographic signals (EEG) and proposes an algorithm for chaotic signal analysis based on the determination of the Largest Lyapunov Exponent (LLE). The proposed method is validated using various chaotic attractors and achieves a low error rate in LLE estimation even in the presence of noise. Additionally, a supervised machine learning model for epilepsy and seizure detection is proposed and achieves 100% accuracy in different classification cases using only 4 features.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Engineering, Electrical & Electronic
Mike Adams, Nianqiang Li, Yu Huang, Pei Zhou, Ian Henning
Summary: This study provides analytical results for the steady-state solutions and dynamic stability boundaries analysis of spin-polarised vertical-cavity surface-emitting lasers (spin-VCSELs) through simplifying the equations of the spin-flip model. The accuracy of the simplified equations is confirmed by comparing the results with numerical simulations. It is found that the range of spin relaxation rates for potential THz sources is very limited.
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2022)
Article
Optics
Yu Huang, Pei Zhou, NianQiang Li
Summary: A high-speed secure key distribution (SKD) scheme based on polarization-keying chaos synchronization in vertical-cavity surface-emitting lasers (VCSELs) is proposed and demonstrated numerically; high-quality chaos synchronization can be achieved without external feedback when response lasers have the same polarization ellipticity; the open-loop configuration in commonly driven lasers results in a short synchronization recovery time, enabling a 1.34 Gb/s SKD with a low bit error ratio.
Article
Chemistry, Multidisciplinary
Krishan Harkhoe, Guy Verschaffelt, Guy Van der Sande
Summary: Delay-based reservoir computing using spin-VCSELs allows high-speed computing. The delay time and feedback rate significantly influence the nonlinear dynamics at short time scales. The system shows superior performance in time series prediction tasks.
APPLIED SCIENCES-BASEL
(2021)
Article
Mathematics, Interdisciplinary Applications
Shilalipi Sahoo, Binoy Krishna Roy
Summary: This paper proposes a new design technique to generate multi-wing chaotic attractors from two-wing chaotic attractors, and the number of wings can be changed by varying the number of equilibrium points and the parameters of the newly added nonlinear function. The new multi-wing chaotic systems have a higher value of the largest Lyapunov exponent, and the largest Lyapunov exponent increases with the variation of a system parameter.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Physics, Multidisciplinary
Shuang Zhou, Xingyuan Wang
Summary: This paper presents a simple method based on perturbing the initial value to directly estimate the largest Lyapunov exponent. The method reduces parameter errors and is feasible and easy to implement without computing the Jacobian matrix and phase space.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Chemistry, Physical
Artur Dabrowski, Tomasz Sagan, Volodymyr Denysenko, Marek Balcerzak, Sandra Zarychta, Andrzej Stefanski
Summary: Controlling stability of dynamical systems is a crucial challenge in science and engineering, often achieved through studying and developing numerical algorithms of control methods. Lyapunov exponents are commonly used to characterize systems' stability, with the largest Lyapunov exponent being key in determining stability. Recent research has shown that the largest Lyapunov exponent can be estimated from the properties of the vector field using basic mathematical operations, leading to significant efficiency improvements compared to commonly applied algorithms.
Article
Mathematics, Interdisciplinary Applications
Froilan Bolo, Wendell Caramat, Ma Carlota Decena
Summary: This study aims to test Twitter posts as an alternative basis in predicting the president's net satisfaction survey, using Partial Least Squares Regression to examine whether Twitter sentiment data possess chaotic behavior.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Engineering, Electrical & Electronic
Nobuhide Yokota, Kazuhiro Ikeda, Hiroshi Yasaka
Summary: This study proposes and investigates the use of birefringent VCSELs for analog RoF systems, demonstrating the generation of 24GHz carrier and heterodyne detection of square-wave signals. The findings show the potential of applying spin-injected birefringent VCSELs for ultra-high-frequency modulation in analog RoF systems.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2021)
Article
Optics
Yao Zeng, Pei Zhou, Yu Huang, Penghua Mu, Nianqiang Li
Summary: In this study, we propose and numerically demonstrate the generation of wideband and high-dimensional chaos signal using optically pumped spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs). We investigate the chaotic characteristics of spin-VCSELs under two scenarios and systematically analyze the influence of key parameters on the chaotic properties. Our simulation results show that spin-VCSELs with simple auxiliary configurations can generate chaos with desired properties, paving the way for potential applications requiring wideband and high-dimensional chaos.
Article
Multidisciplinary Sciences
Jichao Jia, Xue Cao, Xuekai Ma, Jianbo De, Jiannian Yao, Stefan Schumacher, Qing Liao, Hongbing Fu
Summary: This study demonstrates a chiral-emitter-free microcavity circularly polarized organic light-emitting diode (CP-OLED) with high dissymmetry factor and luminance. By embedding a thin two-dimensional organic single crystal layer between two metallic mirrors, controllable spin-splitting with circularly polarized dispersions is achieved. This strategy opens up opportunities for practical applications of on-chip microcavity CP-OLEDs.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Applied
M. Drong, T. Fordos, H. Y. Jaffres, J. Perina, K. Postava, P. Ciompa, J. Pistora, H-J Drouhin
Summary: This study presents a semiclassical model for spin-injected vertical-cavity surface-emitting lasers with local optical anisotropies, focusing on highly anisotropic spin lasers. A generalized matrix formalism for extracting laser modes and a coupled-mode theory for studying time dependence of laser modes are introduced. The theory, based on circularly polarized optical modes, demonstrates advantages in designing and optimizing spin-VCSEL structures with high-contrast gratings for applications in terahertz range polarization modulation and compact terahertz sources.
PHYSICAL REVIEW APPLIED
(2021)
Article
Physics, Condensed Matter
M. Beens, K. A. de Mare, R. A. Duine, B. Koopmans
Summary: A 'toy model' is presented to describe the spin-polarized hot electron transport and spin pumping processes. The model is used to compare the contributions of these two processes and it is found that spin pumping dominates the injected spin current.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Engineering, Multidisciplinary
K. E. Contreras-Vallejo, J. M. Estudillo-Ayala, J. C. Hernandez-Garcia, D. Jauregui-Vazquez, J. M. Sierra-Hernandez, Y. Lopez-Dieguez, D. Tentori, J. R. Reyes Ayona, R. Rojas-Laguna
Summary: This study investigates a deflection laser sensor using pump light source polarization control for tuning an erbium-doped fiber laser. By controlling the polarization state of the pump source, the tuning of the laser can be better controlled. The sensor demonstrates potential applications in bionic and robotic detection fields due to its high sensitivity, good linearity, simple fabrication, and low cost.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2023)
Article
Computer Science, Information Systems
Nianqiang Li, Dimitris Alexandropoulos, Hadi Susanto, Ian Henning, Michael Adams
Article
Optics
L. D. Dogkas, T. Kamalakis, P. Kanakis, D. Alexandropoulos
Article
Optics
Leonidas Dogkas, Thomas Kamalakis, Dimitris Alexandropoulos
Article
Engineering, Electrical & Electronic
G. Mourkioti, P. D. Georgiou, T. Kamalakis, D. Alexandropoulos
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2019)
Article
Optics
Leonidas Dogkas, Thomas Kamalakis, Dimitris Alexandropoulos
OPTICS COMMUNICATIONS
(2019)
Article
Engineering, Electrical & Electronic
Dimitris Alexandropoulos, Simone Mazzucato, Evangelos Karoutsos, Carlo Tessaro, Christina (Tanya) Politi, Nikolaos Vainos
MICROELECTRONIC ENGINEERING
(2020)
Article
Engineering, Electrical & Electronic
Aggeliki Anastasiou, Evangelia Zacharaki, Dimitris Alexandropoulos, Konstantinos Moustakas, Nikolaos A. Vainos
MICROELECTRONIC ENGINEERING
(2020)
Article
Optics
Konstantina Tourlouki, Vasiliki Tsavatopoulou, Dimitris Alexandropoulos, Ioannis D. Manariotis, Simone Mazzucato
Article
Engineering, Electrical & Electronic
Mike Adams, Rihab Al Seyab, Ian Henning, Hadi Susanto, Martin Vaughan
Summary: Studying the simplified rate equation models for coupled laser pairs can provide approximate solutions and explicit expressions for the boundaries of stable dynamics. This is important for understanding the dynamics of two-element VCSEL arrays and the effects of material, device, and operating conditions.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2022)
Article
Engineering, Mechanical
Panagiotis Georgiou, Christos Tselios, Georgia Mourkioti, Charalampos Skokos, Dimitris Alexandropoulos
Summary: This study numerically investigates the chaotic dynamics of optically pumped quantum-dot spin vertically coupled surface emitting lasers, considering both ground state and excited state energy levels. The intensity dynamics of excited state and ground state transitions are studied through the elaboration of a spin-flip model, and it is found that although they exhibit similar nonlinear dynamics, they are weakly correlated, which can be utilized for implementing various functionalities.
NONLINEAR DYNAMICS
(2021)
Article
Telecommunications
Kostas Blekos, Anastasios Tsakas, Christos Xouris, Ioannis Evdokidis, Dimitris Alexandropoulos, Christos Alexakos, Sofoklis Katakis, Andreas Makedonas, Christos Theoharatos, Aris Lalos
Summary: The intensification and expansion of olive cultivation have led to the significant spread of Verticillium wilt, the most important fungal problem affecting olive trees. Recent studies have shown that innovative natural minerals and beneficial microorganisms can restore the health of infected trees, but early detection and marking of infested trees remain challenging.
JOURNAL OF SENSOR AND ACTUATOR NETWORKS
(2021)
Proceedings Paper
Engineering, Electrical & Electronic
Panagiotis D. Georgiou, Dimitris Alexandropoulos, Charalampos Skokos
2020 22ND INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON 2020)
(2020)
Article
Chemistry, Multidisciplinary
Apostolis Verykios, Michael Papadakis, Anastasia Soultati, Maria-Christina Skoulikidou, George Papaioannou, Spyros Gardelis, Ioannis D. Petsalakis, Giannoula Theodorakopoulos, Vasilis Petropoulos, Leonidas C. Palilis, Mihalis Fakis, Nikolaos A. Vainos, Dimitris Alexandropoulos, Dimitris Davazoglou, George Pistolis, Panagiotis Argitis, Athanassios G. Coutsolelos, Maria Vasilopoulou
Proceedings Paper
Engineering, Electrical & Electronic
Nianqiang Li, Dimitris Alexandropoulos, Hadi Susanto, Ian Henning, Michael Adams
Article
Physics, Applied
Anastasia Soultati, Ioannis Kostis, Giorgos Papadimitropoulos, Angelos Zeniou, Evangelos Gogolides, Dimitris Alexandropoulos, Nikos Vainos, Dimitris Davazoglou, Thanassis Speliotis, Nikolaos A. Stathopoulos, Panagiotis Argitis, Maria Vasilopoulou
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2017)
