Guy Van der Sande

Guy Van der Sande
Vrije Universiteit Brussel | VUB · Applied Physics (APHY)

About

170
Publications
17,107
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3,584
Citations

Publications

Publications (170)
Article
In photonic reservoir computing, semiconductor lasers with delayed feedback have shown to be suited to efficiently solve difficult and time-consuming problems. The input data in this system is often optically injected into the reservoir. Based on numerical simulations, we show that the performance depends heavily on the way that information is enco...
Preprint
Full-text available
Ising machines are a promising non-von-Neumann computational concept for neural network training and combinatorial optimization. However, while various neural networks can be implemented with Ising machines, their inability to perform fast statistical sampling makes them inefficient for training these neural networks compared to digital computers....
Article
Full-text available
We present a method to improve the performance of a reservoir computer by keeping the reservoir fixed and increasing the number of output neurons. The additional neurons are nonlinear functions, typically chosen randomly, of the reservoir neurons. We demonstrate the interest of this expanded output layer on an experimental opto-electronic system su...
Article
Full-text available
Ising machines based on nonlinear analog systems are a promising method to accelerate computation of NP-hard optimization problems. Yet, their analog nature is also causing amplitude inhomogeneity which can deteriorate the ability to find optimal solutions. Here, we investigate how the system's nonlinear transfer function can mitigate amplitude inh...
Article
Full-text available
Delay-based reservoir computing (RC), a neuromorphic computing technique, has gathered lots of interest, as it promises compact and high-speed RC implementations. To further boost the computing speeds, we introduce and study an RC setup based on spin-VCSELs, thereby exploiting the high polarization modulation speed inherent to these lasers. Based o...
Conference Paper
We demonstrate the exploitation of dynamically changing speckle patterns for the implementation of a space division multiplexing scheme and for performing photonic computation within the framework of reservoir computing.
Preprint
Ising machines based on nonlinear analog systems are a promising method to accelerate computation of NP-hard optimization problems. Yet, their analog nature is also causing amplitude inhomogeneity which can deteriorate the ability to find optimal solutions. Here, we investigate how the system's nonlinear transfer function can mitigate amplitude inh...
Article
The recent progress in artificial intelligence has spurred renewed interest in hardware implementations of neural networks. Reservoir computing is a powerful, highly versatile machine learning algorithm well suited for experimental implementations. The simplest highperformance architecture is based on delay dynamical systems. We illustrate its powe...
Article
Full-text available
Synchronization of chaotic photonic systems can be used, practically indefinitely, to create and distribute unique encryption keys (one−time pads). However, typical photonic systems are highly susceptible to phase fluctuations and fundamentally limited in their key-generation rate. In this work, the authors demonstrate a fundamentally different app...
Article
Full-text available
Photonic delay-based reservoir computing (RC) has gained considerable attention lately, as it allows for simple technological implementations of the RC concept that can operate at high speed. In this paper, we discuss a practical, compact and robust implementation of photonic delay-based RC, by integrating a laser and a 5.4 cm delay line on an InP...
Article
Full-text available
Reservoir computing has rekindled neuromorphic computing in photonics. One of the simplest technological implementations of reservoir computing consists of a semiconductor laser with delayed optical feedback. In this delay-based scheme, virtual nodes are distributed in time with a certain node distance and form a time-multiplexed network. The infor...
Chapter
We present an encryption and authentication scheme suitable for ASIC or FPGA hardware implementation, which is based on the generalized synchronization of systems showing chaotic dynamical behavior. The scheme consists of a single‐driver system, which provides two identical driven systems with a complex waveform. The driven and driving systems sync...
Article
Full-text available
In optical communications the transmission bandwidth of single mode optical fibers is almost fully exploited. To further increase the capacity of a telecommunication link, multiplexing techniques can be applied across 5 physical dimensions: amplitude, quadrature, polarization, frequency and space, with all but the latter being nearly exhausted. We...
Article
Delay-based reservoir computing is a neuromorphic computing technique employing a single nonlinear node, in this case a semiconductor laser subjected to a delayed optical self-feedback. This implementation of reservoir computing, while being versatile and highly performant, is limited in processing speed by the delay length. In an effort to reduce...
Article
Full-text available
We discuss the sensitivity to optical feedback of a semiconductor ring laser that is made to emit in a single-longitudinal mode by applying on-chip filtered optical feedback in one of the directional modes. The device is fabricated on a generic photonics integration platform using standard components. By varying the filtered feedback strength, we c...
Article
Full-text available
We investigate, both numerically and experimentally, the usefulness of a distributed non-linearity in a passive coherent photonic reservoir computer. This computing system is based on a passive coherent optical fiber-ring cavity in which part of the non-linearities are realized by the Kerr non-linearity. Linear coherent reservoirs can solve difficu...
Preprint
We investigate, both numerically and experimentally, the usefulness of a distributed nonlinearity in a passive coherent photonic reservoir computer. This computing system is based on a passive coherent optical fiber-ring cavity in which part of the nonlinearities are realized by the Kerr nonlinearity. Linear coherent reservoirs can solve difficult...
Article
Full-text available
Coherent Ising machines (CIMs) constitute a promising approach to solve computationally hard optimization problems by mapping them to ground state searches of the Ising model and implementing them with optical artificial spin-networks. However, while CIMs promise speed-ups over conventional digital computers, they are still challenging to build and...
Book
Full-text available
Photonics has long been considered an attractive substrate for next generation implementations of machine-learning concepts. Reservoir Computing tremendously facilitated the realization of recurrent neural networks in analogue hardware. This concept exploits the properties of complex nonlinear dynamical systems, giving rise to photonic reservoirs i...
Preprint
Photonic delay-based reservoir computing (RC) has gained considerable attention lately, as it allows for simple technological implementations of the RC concept that can operate at high speed. In this paper, we discuss a practical, compact and robust implementation of photonic delay-based RC, by integrating a laser and a 5.4cm delay line on an InP p...
Preprint
Full-text available
We present an encryption and authentication scheme suitable for ASIC or FPGA hardware implementation, which is based on the generalized synchronization of systems showing chaotic dynamical behavior. The scheme consists of a single driver system, which provides two identical driven systems with a complex waveform. The driven and driving systems sync...
Data
This file is an animated gif of a random network of 16 demonstration NRMMVs. Save and drop in a browser to see the action.
Data
This zip file contains three short guitar sounds to demonstrate the Real-time Cascaded Reservoirs as described in: "Real-time Audio Processing with a Cascade of Discrete-Time Delay Line-Based Reservoir Computers" Cognitive Computation 9(11), 2017. excitation.wav: clean, as recorded from the guitar, response.wav: response by the guitar amplifier...
Article
Full-text available
We numerically investigate the influence of an integrated filtered optical feedback on the behavior of a semiconductor ring laser subject to external optical injection. The optical injection is spectrally directed at one of the non-lasing longitudinal modes of the laser. This so-called side-mode injection can cause wavelength switching, directional...
Article
Full-text available
Retriggerable and non-retriggerable monostable multivibrators are simple timers with a single characteristic, their period. Motivated by the fact that monostable multivibrators are implementable in large quantities as counters in digital programmable hardware, we set out to investigate their applicability as building blocks of artificial neural net...
Article
Full-text available
We discuss the design and testing of a laser integrated with a long on-chip optical feedback section. The device and feedback section have been fabricated on a generic photonic integration platform using only standard building blocks. We have been able to integrate a 10 cm feedback length on a footprint of 5.5mm². By controlling the amount of feedb...
Article
Full-text available
Background: Real-time processing of audio or audio-like signals is a promising research topic for the field of machine learning, with many potential applications in music and communications. We present a cascaded delay line reservoir computer capable of real-time audio processing on standard computing equipment, aimed at black-box system identifica...
Article
Full-text available
We review a novel paradigm that has emerged in analogue neuromorphic optical computing. The goal is to implement a reservoir computer in optics, where information is encoded in the intensity and phase of the optical field. Reservoir computing is a bio-inspired approach especially suited for processing time-dependent information. The reservoir's com...
Article
Full-text available
We present a novel encryption scheme, wherein an encryption key is generated by two distant complex nonlinear units, forced into synchronization by a chaotic driver. The concept is sufficiently generic to be implemented on either photonic, optoelectronic or electronic platforms. The method for generating the key bitstream from the chaotic signals i...
Article
Reservoir computing (RC) systems are computational tools for information processing that can be fully implemented in optics. Here, we experimentally and numerically show that an optically pumped laser subject to optical delayed feedback can yield similar results to those obtained for electrically pumped lasers. Unlike with previous implementations,...
Article
With the development of new applications using semiconductor ring lasers (SRLs) subject to optical feedback, the stability properties of their outputs becomes a crucial issue. We propose a systematic bifurcation analysis in order to properly identify the best parameter ranges for either steady or self-pulsating periodic regimes. Unlike conventional...
Conference Paper
It is well known that the performance of semiconductor lasers is very sensitive to external optical feedback. This feedback can lead to changes in lasing characteristics and a variety of dynamical effects including chaos and coherence collapse. One way to avoid this external feedback is by using optical isolation, but these isolators and their pack...
Article
We consider nonlinear rate equations appropriate for a quantum cascade laser subject to optical feedback. We analyze the conditions for a Hopf bifurcation in the limit of large values of the delay. We obtain a simple expression for the critical feedback rate that highlights the effects of key parameters such as the linewidth enhancement factor and...
Article
In this letter, we discuss the near-field, far-field, and spatial coherence properties of pulsed broad-area red vertical-cavity surface-emitting lasers (VCSELs) emitting at 680 nm. We will show experimentally that the spatial coherence of the tested devices is strongly reduced when using a pulsed pump current. Under these conditions, the VCSEL emit...
Conference Paper
Since the original demonstration of terahertz quantum-cascade lasers (QCLs), the performance of these devices has shown rapid improvement. QCLs can now deliver milliwatts or more of continuous-wave radiation throughout the terahertz frequency range (300 GHz to 10 THz). Therefore, QCLs have become widely used in various applications such as spectros...
Conference Paper
Tunable laser diodes are needed in a range of applications including wavelength division multiplexing, optical instrument testing, optical sensing and tera hertz generation. In this work, we investigate the stability of lasers which use filtered optical feedback for wavelength tuning. We investigate experimentally the dynamics induced by this on-chi...
Conference Paper
Delay systems subject to delayed optical feedback have recently shown great potential in solving computationally hard tasks. By implementing a neuro-inspired computational scheme relying on the transient response to optical data injection, high processing speeds have been demonstrated. However, reservoir computing systems based on delay dynamics di...
Article
Optical implementations of reservoir computing systems are very promising because of their high processing speeds and the possibility to process several tasks in parallel. These systems can be implemented using semiconductor lasers subject to optical delayed feedback and optical injection. While the amount of the feedback/injection can be easily co...
Article
We experimentally and numerically study the influence of external optical feedback on semiconductor ring lasers which are wavelength tunable using on-chip filtered optical feedback. We investigate the dynamics in the laser’s intensity due to conventional optical feedback and how this dynamics is changed by adding filtered optical feedback. Experime...
Article
Full-text available
We have modified an otherwise standard onetransistor self-biasing resistor-capacitor phase-shift oscillator to induce chaotic oscillations. The circuit uses only two transistors, no inductors, and is powered by a single supply voltage. As such it is an attractive and low-cost source of chaotic oscillations for many applications. We compare experime...
Article
We report results on the asymptotic, bifurcation and numerical analysis of semiconductor ring lasers with negative optoelectronic feedback or incoherent optical feedback. We find that the dynamical behavior of both systems can be adequately described by two differential equations and one map with time delay on time-scales longer than the relaxation...
Article
In this brief, we numerically demonstrate a photonic delay-based reservoir computing system, which processes, in parallel, two independent computational tasks even when the two tasks have unrelated input streams. Our approach is based on a single-longitudinal mode semiconductor ring laser (SRL) with optical feedback. The SRL emits in two directiona...
Article
We numerically show the quantitative relation between the chaos bandwidth enhancement and fast phase dynamics in semiconductor lasers with optical feedback and optical injection. The injection increases the coupling between the intensity and the phase leading to a competition between the relaxation oscillation (RO) frequency and the intrinsic respo...
Conference Paper
Full-text available
We added a small subcircuit to an otherwise standard one-transistor self-biasing resistor-capacitor (RC) phase-shift oscillator to induce chaotic oscillations in four dimensions. The final circuit that we have designed uses only two transistors, no inductors, and is powered by a single supply voltage. As such it is an attractive and low-cost source...
Conference Paper
In this work, we study theoretically the dynamical behavior of two semiconductor ring lasers (SRLs). One is subject to negative optoelectronic feedback and the other laser is subject to incoherent optical feedback. Relying on asymptotic methods, we are able to reduce the original set of five equations used to describe the dynamical behavior of SRLs...
Conference Paper
We investigate different scenarios leading to simultaneous time-delay concealment both in the intensity and the phase dynamics generated from semiconductor ring lasers (SRLs) subject to delayed feedback. Under appropriate conditions, we found that the delay signature can be eliminated both in the intensity and the phase dynamics of SRLs with cross-...
Conference Paper
Semiconductor ring lasers are semiconductor lasers where the laser cavity consists of a ring-shaped waveguide. SRLs are highly integrable and scalable, making them ideal candidates for key components in photonic integrated circuits. SRLs can generate light in two counterpropagating directions between which bistability has been demonstrated. Hence,...
Conference Paper
Delay systems subject to delayed optical feedback have recently shown great potential in solving computationally hard tasks. By implementing a neuro-inspired computational scheme relying on the transient response to optical data injection, high processing speeds have been demonstrated. However, reservoir computing systems based on delay dynamics di...
Article
Full-text available
Semiconductor lasers subject to delayed optical feedback have recently shown great potential in solving computationally hard tasks. By optically implementing a neuro-inspired computational scheme, called reservoir computing, based on the transient response to optical data injection, high processing speeds have been demonstrated. While previous effo...
Article
Full-text available
Reservoir computing is a novel bio-inspired computing method, capable of solving complex tasks in a computationally efficient way. It has recently been successfully implemented using delayed feedback systems, allowing to reduce the hardware complexity of brain-inspired computers drastically. In this approach, the pre-processing procedure relies on...