Search

International audience; Large-scale spatiotemporal photonic reservoir computer (RC) systems offer remarkable solutions for massively parallel processing of a wide variety of hard real-world tasks. In such systems, neural networks are created by either optical or electronic coupling. Here, we investigate the impact of the optical coherence on the performance of large-scale spatiotemporal photonic RCs by comparing a coherent (optical coupling between the reservoir nodes) and incoherent (digital coupling between the reservoir nodes) RC systems. Although the coherent configuration offers significant reduction on the computational load compared to the incoherent architecture, for image and video classification benchmark tasks, it is found that the incoherent RC configuration outperforms the coherent configuration. Moreover, the incoherent configuration is found to exhibit a larger memory capacity than the coherent scheme. Our results pave the way towards the optimization of implementation of large-scale RC systems.

In previous works, it has been shown that reservoir computing (RC) systems using a laser subject to a delayed optical feedback and stabilized by an injected signal may be highly sensitive to the feedback phase. In this Letter, we show that a RC system using a single quantum cascade laser subject to a delayed optical feedback but without injection is robust to the feedback phase for a large range of values of the parameters., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; In this paper, we investigate the possibility of using optical injection to efficiently suppress the time-delay (TD) signatures of chaotic signals in a large experimentally accessible parameter range of semiconductor ring lasers (SRLs). We also study how this optical injection can improve the signal bandwidths. The injection signal is obtained from a master SRL with either optical self-or cross-feedback. For optical self-feedback configurations, it is found that the suppression of TD signatures is similar to what has been found in injected Fabry-Perot semiconductor lasers, i.e., narrow range of parameters with respect to the detuning and injection strengths. For cross-feedback configurations, however, the TD signatures can be suppressed in a wide range of parameters meanwhile the bandwidths are significantly improved for the same range of parameters. This is particularly useful for the security in chaos-based communications and also for generating random bits with improved properties.

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 directional optical modes. Each directional mode processes one individual task to mitigate possible crosstalk. We illustrate the feasibility of our scheme by analyzing the performance on two benchmark tasks: 1) chaotic time series prediction and 2) nonlinear channel equalization. We identify some feedback configurations for which the results for simultaneous prediction/classification indicate a good performance, but with slight degradation (as compared with the performance obtained for single task processing) due to nonlinear and linear interactions between the two directional modes of the laser. In these configurations, the system performs well on both tasks for a broad range of the parameters.

Optoelectronic oscillators based on whispering-gallery mode resonators (WGMRs) are efficient oscillators for ultra-stable microwave generation, in which the energy can be stored in an ultra-high $Q$ -factor resonator instead of the usual long delay line. In this paper, we derive a stochastic model for the calculation of the phase noise performance in these systems considering three different configurations, namely, the case where the energy is stored in high- $Q$ disk-shaped WGMR, the case where energy is stored in an optical delay-line only, and the case for which the energy is stored simultaneously by the resonator and the delay line. Our investigations explain how the WGMR can be optimally used for spurious peak rejection in optoelectronic oscillators. Our experimental measurements are found to be in excellent agreement with analytical and simulation results.

Although the plethora real-life systems modeled by nonlinear systems with two independent time delays, the algebraic expressions for determining the stability of their fixed points remain the Achilles' heel. Typically, the approach for studying the stability of delay systems consists in finding the bifurcation lines separating the stable and unstable parameter regions. This work deals with the parametric construction of algebraic expressions and their use for the determination of the stability boundaries of fixed points in nonlinear systems with two independent time delays. In particular, we concentrate on the cases for which the stability of the fixed points can be ascertained from a characteristic equation corresponding to that of scalar two-delay differential equations, one-component dual-delay feedback, or nonscalar differential equations with two delays for which the characteristic equation for the stability analysis can be reduced to that of a scalar case. Then, we apply our obtained algebraic expressions to identify either the parameter regions of stable microwaves generated by dual-delay optoelectronic oscillators or the regions of amplitude death in identical coupled oscillators.

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, the input data are injected at a time interval that is much larger than the time-delay feedback. These data are directly coupled to the feedback light beam. Our results illustrate possible new avenues for RC implementations for prediction tasks., SCOPUS: ar.j, info:eu-repo/semantics/published

We experimentally and numerically characterize the wavelength switching speed of a tunable semiconductor ring laser using filtered optical feedback. The feedback is realized employing two arrayed-waveguide gratings to split/recombine light into different wavelength channels. The wavelength tuning and switching is controlled by changing the currents injected in semiconductor optical amplifiers in the feedback section. A wavelength switching speed of a few nanoseconds is achieved. We investigate also the effect of the feedback parameters and noise strength on the wavelength switching speed.

International audience; Optoelectronic oscillators are used for a wide variety of applications in microwave photonics. We here report the latest advances in this technology from our research group, with emphasis on the analysis of phase noise performance. We present a stochastic modelling approach for phase noise performance analysis of optoelectronic oscillators based on whispering gallery mode resonators and/or optical fiber delay lines, and the theory is complemented with experimental measurements. We provide a detailed theoretical analysis which enables us to find the stationary states of the system as well as their stability. Our calculations also permit to find explicit formulas for the phase noise spectra, thereby allowing for their optimization. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

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 controlled, it is much more difficult to control the optical feedback/injection phase. We present extensive numerical investigations of the influence of the feedback/injection phases on laser-based reservoir computing systems with feedback. We show that a change in the phase can lead to a strong reduction in the reservoir computing system performance. We introduce a new readout layer design that -at least for some tasks- reduces this sensitivity to changes in the phase. It consists in optimizing the readout weights from a coherent combination of the reservoir's readout signal and its delayed version rather than only from the reservoir's readout signal as is usually done.

Optoelectronic oscillators (OEOs) are microwave photonic systems intended to generate ultra-pure radio-frequency signals for aerospace and communication engineering applications. Typically, a long optical fiber delay line is inserted in the feedback loop as an energy storage element intended to improve the phase noise performance. An ultra-high Q whispering-gallery mode resonator can be inserted as well in order to filter-out the spurious ring-cavity peaks arising in the radio-frequency spectrum. However, dynamical instabilities induced by a relatively large delay have never been analyzed for these OEOs. In this paper, we systematically investigate the stability of the generated microwaves as a function of the effective OEO loop gain and delay. We find that close enough to the oscillation threshold, the generated microwaves are unconditionally stable, but as the gain is increased, their stability becomes dependent on the ratio between the time delay and the overall photon lifetime of the resonator. Our results allow an optimal design for these OEOs, leading to both enhanced spectral stability and phase noise performance., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; We consider an optoelectronic oscillator for ultra-pure microwave generation with two nonlinearly-coupled delay loops in which the output of one of the loops modulates the other. We introduce a suitable dynamical model and study the phase noise performance. Tuning the parameters of the second loop allows us to reduce the detrimental effect of the multiplicative phase noise and damp delay-induced spurious peaks. Also, nonlinear dynamics allows for stable microwave emission with larger amplitude than a single loop system.

8 pages, 15 figures., We analytically and numerically study the effect of an additional feedback in the semiconductor laser used to pump optoelectronic delay devices. We show that this additional feedback renders the system into chaotic regime for a broader parameter range and also induces a stronger chaotic behavior. We study the synchronization of this system as function of the parameter mismatch and show its capability for encoded message transmission., We gratefully thank Vasile Tronciu for helping us with the DDE-BIFTOOL program. As well, financial support from MICINN, Spain, and Feder under Project TEC2006-1009/MIC (PhoDECC) and Project FIS2004-00953 (CONOCE2) and by the EC Project PICASSO (IST-2005-34551) is acknowledged. R.M.Nguimdo also acknoledges the fellowship BES-2007-14627 under the FPI program of MICINN (Spanish Goverment).

We report on an integrated approach to obtain multiwavelength emission from semiconductor ring lasers with filtered optical feedback. The filtered feedback is realized on-chip employing two arrayed-waveguide gratings to split/recombine light into different wavelength channels. Through experimental observations and numerical simulations, we find that the effective gain of the different modes is the key parameter which has to be balanced in order to achieve multiwavelength emission. This can be achieved by tuning the injection current in each amplifier.

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 efforts have focused on signal bandwidths limited by the semiconductor laser's relaxation oscillation frequency, we demonstrate numerically that the much faster phase response makes significantly higher processing speeds attainable. Moreover, this also leads to shorter external cavity lengths facilitating future on-chip implementations. We numerically benchmark our system on a chaotic time-series prediction task considering two different feedback configurations. The results show that a prediction error below 4% can be obtained when the data is processed at 0.25 GSamples/s. In addition, our insight into the phase dynamics of optical injection in a semiconductor laser also provides a clear understanding of the system performance at different pump current levels, even below solitary laser threshold. Considering spontaneous emission noise and noise in the readout layer, we obtain good prediction performance at fast processing speeds for realistic values of the noise strength.

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-feedback even when subject to long delayed feedback. For SRLs with self-feedback configuration, we also found that the concealment of short delay time is possible. The fact that such delay signatures can be eliminated in SRLs subject to short feedback opens the possibility of implementing secure communication schemes and random number generators on chip.

We report on a novel integrated approach to obtain dual wavelength emission from a semiconductor laser based on on-chip filtered optical feedback. Using this approach, we show experiments and numerical simulations of dual wavelength emission of a semiconductor ring laser. The filtered optical feedback is realized on-chip by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifiers are placed in the feedback loop in order to control the feedback strength of each wavelength channel independently. By tuning the current injected into each of the amplifiers, we can effectively cancel the gain difference between the wavelength channels due to fabrication and material dichroism, thus resulting in stable dual wavelength emission. We also explore the accuracy needed in the operational parameters to maintain this dual wavelength emission.

Here, we numerically and experimentally demonstrate that, by combining two post-processing methods (multi-bit extraction and bitwise OR-exclusive (XOR) operations). in a single chaotic semiconductor ring laser (SRL), it is possible to generate true random bits with a bit rate up to 40 Gb/s from a chaos bandwidth of ˜ 2 GHz, thanks to the device ability of lasing in two directional modes and the fact that the two mode signals have low correlations. In addition, SRLs can be easily implemented on chip.

Summary form only given. Optoelectronic oscillators (OEOs) are useful for applications such as radar, time-frequency metrology and lightwave technology, where microwaves with exceptional purity are needed [1]. The purity of microwave signals is achieved thanks to an optical fiber delay-line inserted into the feedback loop providing a quality factor equal to Q = 2π fmT, where fm is the microwave frequency and T the delay. Microwaves with frequencies as large as 75 GHz, and a phase noise lower than -160 dBc/Hz at 10 kHz has been achieved [2]. As Q increases with T, a long delay should improve the performance. However strong parasite ring-cavity peaks at the integer multiples of the round-trip frequency ΩT = 2π/T limiting the region of low phase noise. Alternatives consisting in adding the output of two loops with different delay time has been proposed to lower the phase noise or to reduce the level of parasite ring-cavity peaks [3]. Single-loop OEOs suffer from another severe limitation: increasing the gain the system becomes unstable leading to a modulation of the microwave amplitude and thus to a degradation of the spectral purity [4].Here, we consider a double-loop optoelectronic delay system in which the output of one of the loops is used to modulate the other (Fig. 1) [5]. Besides reducing the phase noise spurious peaks as linearly coupled dual-loop OEOs, this system allows for stable microwave emission with larger amplitude. A semiconductor laser (SL) injects light into a Mach-Zehnder (MZM1). One part of the optical output is delayed by T2 , detected by photodiode PD2, fed to a narrow-band filter with a central frequency Ω0 and bandwidth ΔΩ2, amplified, and used to modulate MZM2. The other part is delayed by T1, optically fed to MZM2, detected by PD1, filtered by an RF filter of central frequency Ω0 and bandwidth ΔΩ1, amplified and finally used to drive the RF electrode of MZM1 closing the loop. The system can be described by the dimensionless amplifier outputs x(t) and y(t) [5] where xt0 = x(t - t0), F(x,φ) = cos[2x(t) + 2φ], du1/dt = x(t), du2/dt = y(t) and G1 and G2 are the overall loop gains. We derive an amplitude equation and determine the parameter region where stable pure microwaves are generated. By including suitable stochastic terms we determine the phase noise performance. As shown in Fig. 1 by appropriately setting the parameters of the second loop, a significant improvement of performance can be achieved comparatively to the single-loop configuration, as the detrimental effect of the multiplicative phase noise can be reduced up to about 18 dB close to the carrier, while delay-induced spurious peaks can be strongly damped.

Semiconductor lasers (SLs) with optical feedback have attracted a lot of attention in the chaos cryptography community due to its capability to develop broadband chaos within which gigabit messages can be encoded [1]. The security of laser-based chaos communications relies mainly on the difficulty of identifying the emitter parameters necessary to build an adequate receiver, which can synchronize with it. In chaos communication schemes based on SLs with delayed optical feedback, the delay time can be identified from time series using standard techniques in most parameter regimes. However, the efforts to enhance the security in these schemes have led to the characterization of a regime in which the delay time appears to be concealed, namely when it is close to the relaxation oscillation period of the laser operating with moderate feedback [2]. These results were obtained exclusively by computing the quantifiers from intensity time series. Taking into account that, in addition to the intensity, the phase information is also transmitted through the public channel, it is mandatory to check if the delay time can be concealed when computing different quantifiers from the phase of the field [3].

The use of the postprocessing method consisting of bitwise Exclusive-OR and least significant bits extraction to generate random bit sequences typically requires two distinct chaotic outputs. While the two signals are, in general, generated using two separated devices, e.g. two Fabry-Perot lasers, a single semiconductor ring laser can be used as an alternative due to its circular symmetry which facilitates lasing in two counterpropagating mode directions. We consider a chaotic semiconductor ring laser and investigate both numerically and experimentally its char- acteristics for fast random bit generation. In particular, we show that by sampling each directional mode's output signal using a 8-bit analog-digital converter and through Exclusive-OR operation applied to the two resulting signals (after throwing away 4 most significant bits), we can achieve fast random bit-streams with a bit rate 4 × 10 = 40 Gbit/s, passing the statisti- cal randomness tests. To optimize the system performance, we also study the dependence of randomness on the main system parameters and on noise.

OCIS codes:250.0250,060.0060,140.0140,190.0190), We consider an electro-optic phase chaos system with two feedback loops organized in a parallel configuration such that the dynamics of one of the loops remains internal. We show that this configuration intrinsically conceals in the transmitted variable the internal delay times, which are critical for decoding. The scheme also allows for the inclusion, in a very efficient way, of a digital key generated as a long pseudorandom binary sequence. A single digital key can operate both in the internal and transmitted variables leading to a large sensitivity of the synchronization to a key-mismatch. The combination of intrinsic delay time concealment and digital key selectivity provides the basis for a large enhancement of the confidentiality in chaos-based communications. © 2012 OSA, The authors thank L. Larger for valuable discussions. Financial support from MINECO, Spain, and Feder under Projects FIS2007-60327 (FISICOS) and TEC2009-14101 (DeCoDicA) and by the EC Project PHOCUS (FP7-ICT-2009-C-240763) is acknowledged. R.M.N. acknowledges fellowship BES-2007-14627 under the FPI program of MINECO. Also, he acknowledges the Research Foundation Flanders (FWO) for project support and fellowships, and the Belgian Interuniversity Attraction Pole Network photonics@be.

PACS numbers: 42.15.Eq, 05.45.Jn, 05.45.Tp, 05.45.Vx, We introduce a scheme that integrates a digital key in a phase-chaos electro-optical delay system for optical chaos communications. A pseudorandom binary sequence (PRBS) is mixed within the chaotic dynamics in a way that a mutual concealment is performed; e.g., the time delay is hidden by the binary sequence, and the PRBS is also masked by the chaos. In addition to bridging the gap between algorithmic symmetric key cryptography and chaos-based analog encoding, the proposed approach is intended to benefit from the complex algebra mixing between a (pseudorandom) Boolean variable, and another continuous time (chaotic) variable. The scheme also provides a large flexibility allowing for easy reconfigurations to communicate securely at a high bit rate between different systems., Financial support from MICINN, Spain, and Feder under Projects TEC2006-10009 (PhoDeCC), FIS2007- 60327 (FISICOS) and TEC2009-14101 (DeCoDicA) and by EC Project PHOCUS (FP7-ICT-2009-C-240763) is acknowledged. R. M. N. also acknowledges the fellowship BES-2007-14627 under the FPI program of MICINN.

Chaos-based optical communications has no clear counterpart of the digital key in algorithmic cryptography. Typically the chaotic carrier is generated using delayed optical or electro-optical systems. Confidentiality relies on hardware parameters that should be kept secret. Unfortunately, the delay time in itself cannot be a key parameter since it can be identified using autocorrelation function or delayed mutual information (DMI). We propose a scheme based on a double opto-electronic feedback system which allows on one hand to integrate a digital key required for decoding and on the other to conceal the delay time so that it cannot be identified from the time series using the typical methods. The scheme we propose is based on high speed phase chaos [1], with constant intensity and an essentially featureless power spectrum, and includes a send delay line in which a key random bit sequence (RBS) is included. The emitter dynamics is given by the dimensionless variables x(t) and y(t) equation equation where du 1 /dt = x, du 2 /dt = y, m(t) is the message and R(t) the RBS. The parameters are the MZI static phases φ 1 = π/4 and φ 2 = π/8, the feedback strengths β 1 = β 2 = 5, the time delays T 1 = 17 ns and T 2 = 15 ns, the fast (low) filter response times τ 1 = 20 ps (θ 1 = 1.6 µs) and τ 2 = 12.2 ps (θ 2 = 1.6 µs) and the MZI imbalanced time delays δT 1 = 510 ps and δT 2 = 400 ps. Figures. 1 b) and c) display DMI of the chaotic carrier as function of the delay without and with RBS, respectively. It is seen that without RBS, clear peaks appear at time-delays T, T + δT 1 , T + δT 2 and T + δT 1 + δT 2 . However, when RBS is employed, time-delays cannot be identified anymore. Similar results were obtained from the computation of the autocorrelation function. Figures 1 d) and e) show the effects of mismatch η in the key by measuring the root-mean-square synchronization error σ and quality factor, respectively. Considering 10 Gb/s message with amplitude of 0.6 for Fig 1 e), it appears that even 4% of key-mismatch is enough to considerably degrade the synchronization quality. Thus, we have shown that RBS can be an efficient way to both provide further security and conceal the time delays in some electro-optic systems.

We investigate theoretically and experimentally the detrimental e ect of ber dispersion on the synchroniza- tion of an optoelectronic phase chaos cryptosystem. We evaluate the root-mean square synchronization error and the cancellation spectra between the emitter and the re- ceiver in order to characterize the quality of the optical ber communication link. These two indicators explicitly show in temporal and spectral domain how ber dispersion does negatively a ect the phase chaos cancellation at the re- ceiver stage. We demonstrate that the dispersion manage- ment techniques used in conventional optical ber networks, such as dispersion-compensating modules/ bers or disper- sion shifted bers, are also e cient to strongly reduce the detrimental e ects of ber propagation in phase chaos com- munications. This compatibility therefore opens the way to a successful integration of more than 10-Gb/s phase chaos communications systems in existing networks, even when the ber link spans over more than 100 km.

We numerically investigate the possibility of using a coupling to increase the complexity in simplest chaotic two-component electronic circuits operating at high frequency. We subsequently show that complex behaviors generated in such coupled systems, together with the post-processing are suitable for generating bit-streams which pass all the NIST tests for randomness. The electronic circuit is built up by unidirectionally coupling three two-component (one active and one passive) oscillators in a ring configuration through resistances. It turns out that, with such a coupling, high chaotic signals can be obtained. By extracting points at fixed interval of 10 ns (corresponding to a bit rate of 100 Mb/s) on such chaotic signals, each point being simultaneously converted in 16-bits (or 8-bits), we find that the binary sequence constructed by including the 10(or 2) least significant bits pass statistical tests of randomness, meaning that bit-streams with random properties can be achieved with an overall bit rate up to 10×100 Mb/s = 1 Gbit/s (or 2×100 Mb/s =200 Megabit/s). Moreover, by varying the bias voltages, we also investigate the parameter range for which more complex signals can be obtained. Besides being simple to implement, the two-component electronic circuit setup is very cheap as compared to optical and electro-optical systems.

We investigate the possibility of concealing the time-delay signatures in semiconductor ring lasers (SRLs) with external feedback. Through the autocorrelation and delayed mutual information, we report different scenarios leading to simultaneous time-delay concealment both in the intensity and the phase dynamics of such systems. In particular, the fact that such delay signatures can be eliminated in a SRL subject to short feedback constitutes a step toward the possibility of implementing secure communication schemes and random number generators on chip. (C) 2012 Optical Society of America

We study the amplification of a pulse soliton in a discrete nonlinear electrical transmission line using negative nonlinear resistances and inductances linearly varying in space. The numerical simulation is used to solve the resulting set of discrete nonlinear differential equations in each case. In both cases, the dissipative effects of the medium in which it travels are compensated on a short distance of a doped domain. During the crossing of this doped domain, the wave conserves its pulse form and recovers its amplitude when coming out.

Here we introduce a Tb/s physical random bit generator based on an optoelectronic phase-chaos system operating with telecom components.

In this paper, we experimentally and numerically study the dynamics of semiconductor ring lasers that are subjected to long delay and moderate self-feedback. Through varying the pump current or the feedback strength or both, we study the appearance and parameter dependence of low frequency fluctuations in these systems. In particular, we observe different routes to the building up of the initial power amplitude. © 2013 IEEE.

Semiconductor lasers subject to external feedback are known to exhibit a wide variety of dynamical regimes desired for some applications such as chaos cryptography, random bit generation, and reservoir computing. Low-frequency fluctuations is one of the most frequently encountered regimes. It is characterized by a fast drop in laser intensity followed by a gradual recovery. The duration of this recovery process is irregular and of the order of hundred nanoseconds. The average time between dropouts is much larger than the laser system characteristic time-scales. Semiconductor ring lasers are currently the focus of a rapidly thriving research activity due to their unique feature of directional bistability. They can be employed in systems for all-optical switching, gating, wavelength-conversion functions, and all-optical memories. Semiconductor ring lasers do not require cleaved facets or gratings for optical feedback and are thus particularly suited for monolithic integration. We experimentally and numerically address the issue of low-frequency fluctuations considering a semiconductor ring laser in a feedback configuration where only one directional mode is re-injected into the same directional mode, a so-called single self-feedback. We have observed that the system is very sensitive to the feedback strength and the injection current. In particular, the power dropouts are more regular when the pump current is increased and become less frequent when the feedback strength is increased. In addition, we find two different recovery processes after the power dropouts of the low-frequency fluctuations. The recovery can either occur via pulses or in a stepwise manner. Since low-frequency fluctuations are not specific to semiconductor ring lasers, we expect these recovery processes to appear also in VCSELs and edge-emitting lasers under similar feedback conditions. The numerical simulations also capture these different behaviors, where the representation in the phase space of the carriers versus the round trip phase difference gives additional insight into these phenomena. This proceedings paper gives a short overview of the results of L. Mashal et al. [L. Mashal et al., IEEE J. Quantum. Electron. 49, 790, 2013].

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 discussed in the literature are designed by coupling many different stand-alone components which lead to bulky, lack of long-term stability, non-monolithic systems. Here we numerically investigate the possibility of implementing reservoir computing schemes based on semiconductor ring lasers as they are scalable and can be easily implemented on chip. We numerically benchmark our system on a chaotic time-series prediction task. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We report on an integrated approach to achieve fast wavelength switching in a semiconductor ring lasers using on-chip filtered optical feedback. The feedback section consists of two arrayed waveguide gratings and four semiconductor optical amplifiers. The wavelength tuning and switching are controlled by changing the injected currents into the semiconductor optical amplifiers. Experimental observations and numerical simulations show a wavelength switching speed of few nano seconds. We also investigate the effect of the feedback parameters and the noise strength on the wavelength switching speed.