Statistics of the Optical Phase of a Gain-Switched Semiconductor Laser for Fast Quantum Randomness Generation

The statistics of the optical phase of the light emitted by a semiconductor laser diode when subject to periodic modulation of the applied bias current are theoretically analyzed. Numerical simulations of the stochastic rate equations describing the previous system are performed to describe the temporal dependence of the phase statistics. These simulations are performed by considering two cases corresponding to random and deterministic initial conditions. In contrast to the Gaussian character of the phase that has been assumed in previous works, we show that the phase is not distributed as a Gaussian during the initial stages of evolution. We characterize the time it takes the phase to become Gaussian by calculating the dynamical evolution of the kurtosis coefficient of the phase. We show that, under the typical gain-switching with square-wave modulation used for quantum random number generation, quantity is in the ns time scale; that corresponds to the time it takes the system to lose the memory of the distribution of the initial conditions. We compare the standard deviation of the phase obtained with random and deterministic initial conditions to show that their differences become more important as the modulation speed is increased.This research was funded by Ministerio de Economía y Competitividad (MINECO/FEDER,UE), Spain under grant RTI2018-094118-B-C22

Quantum random number generator based on polarization switching in gain-switched VCSELs

We experimentally study a quantum random number generator based on the random excitation of the linearly polarized modes of a gain-switched vertical-cavity surface-emitting laser (VCSEL). Our device is characterized by having polarization switching under continuous wave operation. By measuring the linear polarization mode that is excited in each pulse we collect a sufficient number of bits to evaluate if a standard statistical test suite is passed. We consider linear and Von Neumann post-processing methods in order to reduce the bias with different levels of bits rejection. The post-processed bit strings pass all tests in the standard test suite for random number generators provided by the National Institute of Standards and Technology (NIST). We finally compare the results obtained with different post-processing functions, including several [n, k, d] linear BCH codes. We show that large values of n and k are the best choice to obtain simultaneously improved throughput and randomness.Ministerio de Ciencia e Innovación (PID2019-110633GB-I00MCIN/AEI/10.13039/501100011033, PID2021- 123459OB-C22 MCIN/AEI/FEDER, UE). A. Quirce acknowledges financial support from Beatriz Galindo program, Ministerio de Ciencia, Innovación y Universidades (Spain)

Sistema de generación óptica de señales

Sistema de generación óptica de señales, que comprende un láser esclavo y al menos dos láseres maestros, estando dichos al menos dos láseres maestros configurados para excitar a dicho láser esclavo. El láser esclavo es un láser multimodo, estando el sistema configurado para que dichos al menos dos láseres maestros exciten al menos dos modos de dicho láser multimodo obteniéndose una señal cuya frecuencia está comprendida en el rango que va desde las frecuencias de microondas a las decenas de teraherzios.Solicitud: 201200422 (18.04.2012)Nº Pub. de Solicitud: ES2430488A1 (20.11.2013)Nº de Patente: ES2430488B2 (24.04.2014

VCSEL-Based Optical Frequency Combs Expansion Induced by Polarized Optical Injection

ABSTRACT: The present theoretical work studies optical frequency combs (OFCs) associated with both linear polarizations of a gain switching vertical-cavity surface-emitting laser (VCSEL) subject to optical injection of arbitrary polarization. The overall OFC, formed by the two orthogonally polarized sub-combs, can have an expanded optical span in agreement with experiments reported by Prior et al. We show that the maximum optical span is obtained for a certain angle between the linearly polarized optical injection and the direction of emission of the main mode of the free-running VCSEL. We find that this angle decreases as the injection strength increases. We also characterize the maximum expansion of the optical span of the overall comb. For VCSELs with large birefringence splitting the maximum expansion is the optical span of the free-running OFC, while for small birefringence splitting VCSELs the maximum expansion is the value of the birefringence splitting.This work was funded by the Ministerio de Economía y Competitividad (MINECO/FEDER, UE), Spain under project TEC2015-65212-C3-1-P

Polarization-resolved nonlinear dynamics in long-wavelength single-mode VCSELs subject to orthogonal optical injection

In this work we perform an experimental study of the polarization-resolved nonlinear dynamics of a 1550 nm single-mode linearly polarized VCSEL when subject to orthogonal optical injection. We have measured the stability maps that identify the boundaries between regions of different nonlinear dynamics by using the RF-spectrum of the total power. These maps are measured in the plane of the frequency detuning between the injected light and the orthogonal linear polarization of the VCSEL versus injected power. Stability maps are obtained for two different values of the bias current. Analysis of the dynamics is given in terms of the time traces of the total power and of both linearly polarized output signals. The corresponding RF and optical spectra are also measured. Different dynamical regimes including periodic, period doubling, and irregular dynamics are observed for both polarizations. When the frequency detuning is positive polarization switching can be observed in a periodic dynamical regime, including both period one and period two behaviours. For positive frequency detuning, the only polarization that contributes to the dynamics of the total power is the orthogonal polarization. For negative frequency detuning values both linear polarizations contribute to the dynamics of the total power.The authors acknowledge support from the Ministerio de Ciencia e Innovación under project TEC2009-14581-C02-02. The authors also acknowledge Prof. Krassimir Panajotov from Vrije Universiteit Brussels, Dr. Antonio Hurtado and Prof. Mike Adams from the Univ. of Essex (UK) for fruitful discussions

Transverse mode selection and injection locking in 1550-nm multimode VCSELs induced by optical injection

An experimental investigation of the modal selection induced by optical injection in 1550 nm multitransverse-mode VCSELs is performed. The free-running VCSEL emits in two transverse modes that are linearly polarized in a direction referred as parallel. We consider the situation in which parallel polarized laser light is injected in the VCSEL in order to select its fundamental transverse mode. We analyze the dependence of the modal selection process on the wavelength detuning between the externally injected signal and the fundamental mode. The injected power needed to select the fundamental mode as a function of the wavelength detuning is measured for several values of the bias current. This injected power exhibits a minimum at a positive wavelength detuning. The curves obtained for different bias currents are very close for positive and large wavelength detuning, while they are very separated for smaller detuning. The selection of the fundamental mode can be obtained with a value of the injected power that changes only slightly with the bias current when the wavelength detuning is large and positive. These results indicate that operation at large and positive wavelength detuning is of interest in the long-distance single-mode fiber transmission of multimode injection-locked VCSELs because the selection of the fundamental mode is obtained with an injected power that is almost independent on the VCSEL bias current. Both, the minimum injected power and the wavelength detuning at which it appears increase with the VCSEL bias current. We describe the relation between transverse mode selection and injection locking by comparing the dependence of both phenomena on the wavelength detuning. Modal selection is accompanied by injection locking only for large and positive values of the wavelength detuning. For small detuning values, with the VCSEL biased with a low (high) current, the injected power required for modal selection is lower (higher) than that needed for injection locking.The authors would like to thank Matías Salvide and Marita Torre from the Instituto de Física “Arroyo Seco”, U.N.C.P.B.A. for fruitful discussions. The authors acknowledge support from the Ministerio de Ciencia e Innovación under project TEC2009-14581-C02-02 and from the Marie Curie Intra-European Fellowships for Career Development (IEF), European Commission

Encinares luso-extremadurenses y sus etapas preclimácicas

Se comentan las distintas faciaciones de encinar observadas en la provincia corológico luso-extremadurense, dentro de la serie mesomediterráneo de la encina o Quercus rotundifolia Pyro-Querceto rotundifoliae sigmetumWe comment several faciations holm-oak wood's of the Luso-Extremadurense province belonging to the mesomediterranean series Pyro-Querceto rotundifoliae S

Numerical and Experimental Analysis of Optical Frequency Comb Generation in Gain-Switched Semiconductor Lasers

We have performed a systematic experimental and simulation analysis of the optical frequency combs generated by gain-switching single mode laser diodes, either free-running or subjected to optical injection. The simulations have been produced with a dynamical model consisting of three rate equations that include stochastic noise terms. The model parameters have been extracted from experiments. An exhaustive comparison between the simulated and the experimental temporal profiles and optical spectra generated under a wide range of switching and optical injection conditions has been performed. The excellent quantitative agreement found in the entire range of the explored operating conditions supports the validity of the model for the analysis of the comb generation mechanisms. The detailed maps generated provide guidelines for selecting suitable operating conditions for specific comb characteristics.This work was funded by the Ministerio de Economia y Competitividad of Spain (COMBINA, TEC201565212-C3-1-P and TEC201565212-C3-2-P)

Informática de gestión

Nivel educativo: Grado. Duración (en horas): Más de 50 horasLa asignatura con un total de 6 créditos se divide en 2 tipos de docencia: la magistral y las prácticas de ordenador, a razón de cuatro horas semanales repartidas en dos días o sesiones. A pesar de que la asignación formal es de 12 horas magistrales y 48 horas de prácticas de ordenador, en la práctica llevamos varios años impartiendo toda la docencia como prácticas de ordenador. La asignatura está organizada en 11 temas básicos: Introducción a la gestión empresarial modular, Herramientas de software para la creación y presentación de informes utilizando herramientas de software libre, Gestión de Procesos de Negocio (generalidades), Administración de Productos, Gestión de Almacén, Formalización de las Ventas, Relación con los Clientes, Recursos Humanos: gestión de personal y nóminas, Explotación de la empresa I, Explotación de la empresa II, Prueba e Implementación del modelo. Todos los temas tienen un peso proporcional en el conjunto de la asignatura

Impact of Optimal Timing of Intake of Multi-Ingredient Performance Supplements on Sports Performance, Muscular Damage, and Hormonal Behavior across a Ten-Week Training Camp in Elite Cyclists: A Randomized Clinical Trial

[EN] Multi-ingredient performance supplements (MIPS), ingested pre- or post-workout, have been shown to increase physiological level effects and integrated metabolic response on exercise. The purpose of this study was to determine the efficacy of pre-and post-training supplementation with its own MIPS, associated with CHO (1 g·kg−1) plus protein (0.3 g·kg−1) on exercise-related benchmarks across a training camp for elite cyclists. Thirty elite male cyclists participated in a randomized non-placebo-controlled trial for ten weeks assigned to one of three groups (n = 10 each): a control group treated with CHO plus protein after training (CG); a group treated with MIPS before training and a CHO plus protein after training, (PRE-MIPS); a group treated with CHO plus protein plus MIPS after training, (POST-MIPS). Performance parameters included (VO2max, peak; median and minimum power (W) and fatigue index (%)); hormonal response (Cortisol; Testosterone; and Testosterone/Cortisol ratio); and muscle biomarkers (Creatine kinase (CK), Lactate dehydrogenase (LDH), and Myoglobin (Mb)) were assessed. MIPS administered before or after training (p ≤ 0.05) was significantly influential in attenuating CK, LDH, and MB; stimulating T response and modulating C; and improved on all markers of exercise performance. These responses were greater when MIPS was administered post-workout.S