DSpace Repository :: Browsing by Author "Grosz, Diego"

Browsing by Author "Grosz, Diego"

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Analytical study of coherence in seeded modulation instability
(2016-09) Bonetti, Juan I.; Hernández, Santiago M.; Fierens, Pablo Ignacio; Grosz, Diego
"We derive analytical expressions for the coherence in the onset of modulation instability, in excellent agreement with thorough numerical simulations. As usual, we start by a linear perturbation analysis, where broadband noise is added to a cw pump; then, we investigate the effect of adding a deterministic seed to the cw pump, a case of singular interest as it is commonly encountered in parametric amplification schemes. Results for the dependence of coherence on parameters such as fiber type, pump power, propagated distance, and seed signal-to-noise ratio are presented. Finally, we show the importance of including higher-order linear and nonlinear dispersion when looking at longer-wavelength regions"
Anti-stokes Raman gain enabled by modulation instability in mid-IR waveguides
(2018-11) Sánchez, Alfredo D.; Fierens, Pablo Ignacio; Hernández, Santiago M.; Bonetti, Juan I.; Brambilla, Gilberto; Grosz, Diego
"The inclusion of self-steepening in the linear stability analysis of modulation instability (MI) leads to a power cutoff above which the MI gain vanishes. Under these conditions, MI in mid-IR waveguides is shown to give rise to the usual double-sideband spectrum but with Raman-shaped sidelobes. This results from the energy transfer of a CW laser simultaneously to both stokes and anti-stokes bands in pseudo-parametric fashion. As such, the anti-stokes gain matches completely the stokes profile over the entire gain bandwidth. This remarkable behavior, not expected from an unexcited medium, is shown not to follow from a conventional four-wave mixing interaction between the pump and the Stokes band. We believe this observation to be of relevance in the area of Raman-based sensors, which, in several instances, rely on monitoring small power variations of the anti-stokes spectral component."
Conmutación resistiva
(2014) Oxoby, Juan Manuel; Grosz, Diego
"En este trabajo se estudia el comportamiento del fenómeno de la conmutación resistiva frente a estímulos de corriente contaminados con ruido eléctrico. Se encontró que existe una amplitud de ruido óptima para el cual el mismo tiene efectos positivos. Para realizar los experimentos fue necesario la construcción de un amplificador de transconductancia de gran ancho de banda, para la inyección de pulsos de corriente, y una fuente de ruido blanco gausiano, para simular el ruido eléctrico de origen térmico."
A direct method for the simultaneous estimation of self-steepening and the fractional Raman contribution in fiber optics
(2021-06) Linale, N.; Bonetti, Juan I.; Fierens, Pablo Ignacio; Hernández, Santiago M.; Grosz, Diego
"We propose an original, simple, and direct method for the simultaneous estimation of the selfsteepening parameter and the fractional Raman contribution in fiber optics. Our proposal is based on the dependence of the modulation instability gain on both parameters, as obtained from a linear stability analysis of the newly introduced photon-conserving generalized nonlinear Schrödinger equation (pcGNLSE), and requires only the CW or quasi-CW pumping of the waveguide under test and a few direct spectral measurements. Further, we demonstrate the feasibility of the estimation procedure by means of detailed simulations for typical waveguide parameters in relevant spectral ranges. Last, we discuss the range of applicability of the proposed method and compare its results, advantages, and disadvantages with a recently introduced method based on short-pulse dynamics."
Dispersive waves in optical fibers with a zero-nonlinearity wavelength
(2021-08) Sparapani, Alexis; Linale, N.; Grosz, Diego; Bonetti, Juan I.; Fierens, Pablo Ignacio; Hernández, Santiago M.
"We present results on dispersive waves radiated by solitons in the context of fibers with arbitrary frequency-dependent nonlinearities. In particular, we focus on the effect of a zero-nonlinearity wavelength within the spectral region of interest."
Doubly periodic dispersion maps for 10 and 40 Gbit/s ultra-long-haul transmission
(2004-09) Grosz, Diego; Banerjee, S.; Agarwal, A.; Küng, A. P.; Maywar, D. N.
"Optical transmission employing doubly periodic dispersion maps at 10 and 40 Gbit/s data rates is reported. The implications of these transmission results in providing added degrees of flexibility in network design, in particular, in applications such as optical add-drops and hybrid data rate systems, are discussed. "
Enhanced anti-stokes Raman gain in nonlinear waveguides
(2019) Sánchez, Alfredo D.; Hernández, Santiago M.; Bonetti, Juan I.; Grosz, Diego; Fierens, Pablo Ignacio
"We show that, under certain conditions, modulation instability in nonlinear waveguides gives rise to the usual double-sideband spectral structure, but with a Raman gain profile. This process is enabled by the energy transfer from a strong laser pump to both Stokes and antiStokes sidebands in a pseudo-parametric fashion. We believe this striking behavior to be of particular value in the area of Raman-based sensors which rely on sensitive measurements of the anti-Stokes component".
Experimental investigation of noise-assisted information transmission and storage via stochastic resonance
(2010-05) Patterson, Germán; Goya, Andrés F.; Fierens, Pablo Ignacio; Ibáñez, Santiago Agustín; Grosz, Diego
"We present experimental results on the information transmission and storage via stochastic resonance in circuits designed and built around Schmitt triggers (STs). First, we investigate the performance of a transmission line comprised of five STs and show it to exhibit stochastic resonance. Each ST in the line is fed with white Gaussian noise, and the first ST is driven by a non-return-to-zero pseudo-random bit sequence with sub-threshold amplitude. Parameters such as bit error rate (Q-factor) are measured (calculated) and shown to exhibit a minimum (maximum) for an optimum amount of noise. Interestingly, we find that system performance degrades with the number of STs as if the system were linear and impaired only by additive Gaussian noise. We then propose and build a 1-bit storage device based on two STs in a loop configuration. We demonstrate that such a system is capable of storing one bit of information only in the presence of noise, and that there is a regime where the efficiency of such a device increases with increasing noise. Our results point to the feasibility of building 'blocks' that can transmit, store and eventually process information, whose performance is not only robust against noise, but can actually benefit from it. © 2010 Elsevier B.V. All rights reserved."
A generic model for the study of supercontinuum generation in graphene-covered nanowires
(2022-01) Linale, N.; Fierens, Pablo Ignacio; Vermeulen, N.; Grosz, Diego
"We study supercontinuum (SC) generation in graphene-covered nanowires based on a generic model that correctly accounts for the evolution of the photon number under Kerr and two-photon absorption processes, and the influence of graphene is treated within the framework of saturable photoexcited-carrier refraction. We discuss the role of the various effects on the generation of SC by a thorough analysis of short-pulse propagation in two different kinds of graphene-covered nanowires, one made of silicon nitride and the other made of silicon. Finally, we discuss the effect of stacking graphene layers as a means to enhance SC generation with pulse powers compatible with those in integrated optical devices."
A geometrical view of scalar modulation instability in optical fibers
(2017) Hernández, Santiago M.; Fierens, Pablo Ignacio; Sánchez, Alfredo D.; Grosz, Diego; Bonetti, Juan I.
"Full models of scalar modulation instability (MI) in optical fibers available in the literature usually involve complex formulations. In this paper, we present a novel approach to the analysis of MI in optical fibers by means of a simple geometrical description in the power versus frequency plane. This formulation allows us to relate the shape of the MI gain to any arbitrary dispersion profile of the medium, thus providing a simple insight. As a result, we derive a straightforward explanation of the nontrivial dependence of the cutoff power on high-order dispersion and explicitly derive the power that maximizes the gain. Our approach puts forth a tool to synthesize a desired MI gain with the potential application to a number of parametric-amplification and supercontinuum-generation devices whose initialstage dynamics rely upon MI."
A higher-order perturbation analysis of the nonlinear Schrödinger equation
(2019-06) Bonetti, Juan I.; Hernández, Santiago M.; Fierens, Pablo Ignacio; Grosz, Diego
"A well-known and thoroughly studied phenomenon in nonlinear wave propagation is that of modulation instability (MI). MI is usually approached as a perturbation to a pump, and its analysis is based on preserving only terms which are linear on the perturbation, discarding those of higher order. In this sense, the linear MI analysis is relevant to the understanding of the onset of many other nonlinear phenomena, such as supercontinuum generation, but it has limitations as it can only be applied to the propagation of the perturbation over short distances. In this work, we propose approximations to the propagation of a perturbation, consisting of additive white noise, that go beyond the linear modulation instability analysis, and show them to be in excellent agreement with numerical simulations and experimental measurements."
Impact of DCF properties on system design
(2006) Essiambre, René-Jean; Winzer, Peter J.; Grosz, Diego
"The dispersion-compensating ﬁber is an important optical element of current and future optical networks. In this paper, we review the impact that various properties of dispersion-compensating ﬁbers has on the performance of optical communication systems."
Implementación y caracterización de un sistema óptico de 10 Gbps de bajo costo y su aplicación a enlaces de altas pérdidas
(2015) Benítez, Julio C.; Grosz, Diego
"En esta tesis se presenta una implementación práctica de un sistema óptico de 10 Gbps en su capa física, utilizando para esto electrónica de bajo costo disponible en el mercado: una plataforma de desarrollo FPGA Virtex 5 (como generador de PRBS y medidor de BER) y transceptores SFP+."
Measuring self-steepening with the photon-conserving nonlinear Schrödinger equation
(2020-08-15) Linale, N.; Fierens, Pablo Ignacio; Bonetti, Juan I.; Sánchez, Alfredo D.; Hernández, Santiago M.; Grosz, Diego
"We propose an original, simple, and direct method to measure self-steepening (SS) in nonlinear waveguides. Our proposal is based on results derived from the recently introduced photon-conserving nonlinear Schrödinger equation (NLSE) and relies on the time shift experienced by soliton-like pulses due to SS upon propagation. In particular, a direct measurement of this time shift allows for a precise estimation of the SS parameter. Furthermore, we show that such an approach cannot be tackled by resorting to the NLSE. The proposed method is validated through numerical simulations, in excellent agreement with the analytical model, and results are presented for relevant spectral regions in the near infrared, the telecommunication band, and the mid infrared, and for realistic parameters of available laser sources and waveguides. Finally, we demonstrate the robustness of the proposed scheme against deviations expected in real-life experimental conditions, such as pulse shape, pulse peak power, pulsewidth, and/or higher-order linear and nonlinear dispersion."
Model for frequency-dependent nonlinear propagation in 2D-decorated nanowires
(2021-03) Linale, N.; Bonetti, Juan I.; Sánchez, Alfredo D.; Fierens, Pablo Ignacio; Grosz, Diego
"We show that 2D-decorated silicon nanowires exhibit a strong frequency dependence of the real (Kerr) and imaginary (two-photon absorption) nonlinear coefficients. In this setting, we demonstrate that the usual extension of the nonlinear Schr¨odinger equation used to model propagation in this type of waveguides is rendered inadequate. Hence, we introduce a new modeling framework to tackle the frequency dependence of the nonlinear coefficients in 2D-decorated." nanowires, and present an example of its application to the relevant case of supercontinuum generation in graphene- and graphene-oxide decorated silicon nanowires
Modified nonlinear Schrödinger equation for frequency-dependent nonlinear profiles of arbitrary sign
(2019) Bonetti, Juan I.; Linale, N.; Sánchez, Alfredo D.; Hernández, Santiago M.; Fierens, Pablo Ignacio; Grosz, Diego
In recent times, materials exhibiting frequency-dependent optical nonlinearities, such as nanoparticle-doped glasses and other metamaterials, have gathered significant interest. The simulation of the propagation of intense light pulses in such media, by means of the nonlinear Schrödinger equation (NLSE), poses the problem in that straightforward inclusion of a frequency-dependent nonlinearity may lead to unphysical results, namely, neither the energy nor the photon number is conserved in general. Inspired by a simple quantum-mechanical argument, we derive an energy- and photon-conserving NLSE (pcNLSE). Unlike others, our approach relies only on the knowledge of the frequency-dependent nonlinearity profile and a generalization of Miller’s rule for nonlinear susceptibility, enabling the simulation of nonlinear profiles of arbitrary frequency dependence and sign. Moreover, the proposed pcNLSE can be efficiently solved by the same numerical techniques commonly used to deal with the NLSE. Relevant simulation results supporting our theoretical approach are presented.
Modulation instability in waveguides with an arbitrary frequency-dependent nonlinear coefficient
(2020-05) Linale, N.; Bonetti, Juan I.; Sánchez, Alfredo D.; Hernández, Santiago M.; Fierens, Pablo Ignacio; Grosz, Diego
"In this Letter, we present, for the first time, to the best of our knowledge, the modulation instability (MI) gain spectrum of waveguides with an arbitrary frequency-dependent nonlinear coefficient ensuring strict energy and photon-number conservation of the parametric process. This is achieved by starting from a linear stability analysis of the recently introduced photon-conserving nonlinear Schrödinger equation. The derived MI gain is shown to predict some unique features, such as a nonzero gain extending beyond a zero-nonlinearity wavelength and a complex structure of the MI gain spectrum. Analytical results are shown to be in excellent agreement with numerical simulations."
Narrowband and ultra-wideband modulation instability in nonlinear metamaterial waveguides
(2020-11-01) Linale, N.; Fierens, Pablo Ignacio; Hernández, Santiago M.; Bonetti, Juan I.; Grosz, Diego
"Waveguides based on metamaterials may exhibit strongly frequency-dependent nonlinearities. In this work, we focus on the phenomenon of modulation instability in this type of waveguide, departing from a new modeling equation that ensures strict conservation of both the energy and photon number of the parametric process. In particular, we analyse the case of a waveguide with a linearly frequency-dependent nonlinear coefficient, revealing unique features such as narrowband and ultra-wideband gain spectra and the suppression of the power cutoff giving rise to an ever-growing MI gain. These markedly distinct regimes are enabled by self-steepening (SS) and manifest themselves depending upon the magnitude and sign of the SS parameter.We believe these findings to be most relevant in the context of mid-IR supercontinuum sources."
Noise on resistive switching: a Fokker–Planck approach
(2016-05) Patterson, Germán; Grosz, Diego; Fierens, Pablo Ignacio
"We study the effect of internal and external noise on the phenomenon of resistive switching. We consider a non-harmonic external driving signal and provide a theoretical framework to explain the observed behavior in terms of the related Fokker–Planck equations. It is found that internal noise causes an enhancement of the resistive contrast and that noise proves to be advantageous when considering short driving pulses. In the case of external noise, however, noise only has the effect of degrading the resistive contrast. Furthermore, we find a relationship between the noise amplitude and the driving signal pulse width that constrains the persistence of the resistive state. In particular, results suggest that strong and short driving pulses favor a longer persistence time, an observation that may find applications in the field of high-integration high-speed resistive memory devices."
Noise-assisted multibit storage device
(2011-08-29) Bellomo, Guido; Patterson, Germán; Fierens, Pablo Ignacio; Grosz, Diego
In this Letter we extend our investigations on noise-assisted storage devices through the experimental study of a loop composed of a single Schmitt trigger and an element that introduces a finite delay. We show that such a system allows the storage of several bits and does so more efficiently for an intermediate range of noise intensities. Finally, we study the probability of erroneous information retrieval as a function of elapsed time and show a way for predicting device performance independently of the number of stored bits.

Browsing by Author "Grosz, Diego"

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