Spontaneous decay rates in active waveguides

We present a new method to measure the guided, radiated and total decay rates in one-dimensional waveguides. It is also theoretically shown that large modifications of the total decay rate can be achieved in realistic EDFAs and EDWAs with effective mode area radii smaller than ~ 1 micrometer.Comment: 3 pages, latex, 2 figures, 1 table, title change, published versio

Modeling non linear propagation in optical fibers : data transmission systems and optical parametric amplifiers

Orientador: Hugo Luis FragnitoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb WataghinResumo: Apresentamos métodos para a otimização das simulações da propagação não linear da luz em fibras ópticas a través do Método de Split-Step Fourier (SSFM). Os dois efeitos considerados na modelagem da propagação são a dispersão e o efeito Kerr instantâneo. Estudamos tanto as equações acopladas considerando os dois modos principais de polarização quanto as equações escalares, estas últimas aplicáveis em situações em que o campo pode ser considerado um escalar, como em fibras isotrópicas com todos os campos linearmente polarizados e paralelos. Mostramos que o método que propomos para resolver as equações escalares é ordens de grandeza mais rápido do que outros métodos apresentados recentemente na literatura científica na modelagem de sistemas de transmissão de dados. No caso das equações acopladas, mostramos que o método proposto fornece resultados acurados na modelagem de amplificadores paramétricos e o utilizamos para validar um modelo analítico de seis ondas que nós mesmos desenvolvemos. Também utilizamos o método proposto para as equações acopladas para estudar o impacto das variações aleatórias da birrefringência sobre o ganho de amplificadores paramétricos, mostrando a importância da modelagem realista destas flutuações. Todos os códigos desenvolvidos são disponibilizados e distribuídos sob uma licença do tipo de software livre através de um portal criado na internet especialmente para esse fimAbstract: We introduce optimized models and algorithms for the simulation of non linear propagation in optical fibers using the split-step Fourier Method (SSFM). Dispersion and the Kerr effect are the two main effects considered in the simulations. We study the coupled equations, considering both polarization modes, as well as the scalar equation, which can be applied when the scalar approximation holds, as in isotropic fibers with all fields linearly polarized and parallels. We show that the method that we propose to solve the scalar equation is orders of magnitude faster than other methods recently introduced in the scientific literature for modeling transmission systems. In the coupled-equations case, we show that the proposed method gives accurate results for the modeling of parametric amplifiers, and use it to validate an analytical six-wave model that we developed. We also use the method for the coupled-equations to study the effects of randomly varying birefringence on parametric amplifiers gain, showing the importance of the accurate modeling of these fluctuations. All the codes developed in this thesis are available for download and distributed under a creative commons license in an internet site created specifically for this purposeDoutoradoÓticaDoutor em Ciência

Optimum Integration Procedure for Connectionist and Dynamic Field Equations

Connectionist and dynamic field models consist of a set of coupled first-order differential equations describing the evolution in time of different units. We compare three numerical methods for the integration of these equations: the Euler method, and two methods we have developed and present here: a modified version of the fourth-order Runge Kutta method, and one semi-analytical method. We apply them to solve a well-known nonlinear connectionist model of retrieval in single-digit multiplication, and show that, in many regimes, the semi-analytical and modified Runge Kutta methods outperform the Euler method, in some regimes by more than three orders of magnitude. Given the outstanding difference in execution time of the methods, and that the EM is widely used, we conclude that the researchers in the field can greatly benefit from our analysis and developed methods.Fil: Rieznik, Andrés Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva y Traslacional. Fundación Ineco Rosario Sede del Incyt | Instituto de Neurología Cognitiva. Instituto de Neurociencia Cognitiva y Traslacional. Fundación Ineco Rosario Sede del Incyt | Fundación Favaloro. Instituto de Neurociencia Cognitiva y Traslacional. Fundación Ineco Rosario Sede del Incyt; ArgentinaFil: Di Tella, Rocco. Universidad de Buenos Aires; ArgentinaFil: Schvartzman, Lara. Universidad de Buenos Aires; ArgentinaFil: Babino, Andrés. The Rockefeller University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Introduction to quantum cryptography

We show in details the four quantum key distribution protocols which initiated the important field of quantum cryptography, using an accessible language for undergraduate students. We begin presenting the BB84 protocol, which uses polarization states of photons in order to transmit cryptographic keys. Thereupon we show the E91 protocol, whose security is based on the use of singlet states to generate a random sequence of bits. We end the paper with the BBM92 and the B92 protocol. These last two protocols can be seen as simplified versions of the first two.Apresentamos de maneira detalhada os quatro protocolos de distribuição de chaves que fundaram a importante área da criptografia quântica, numa linguagem acessível a alunos de graduação em Física. Começamos pelo protocolo BB84, o qual se utiliza de estados de polarização de fótons para transmitir chaves criptográficas. Em seguida, apresentamos o protocolo E91, que faz uso de singletos para gerar uma seqüência de números aleatórios. Finalizamos este artigo apresentando o protocolo BBM92 e o B92, os quais podem ser vistos como simplificações dos dois primeiros protocolos.51752

High-speed tunable photonic crystal fiber-based femtosecond soliton source without dispersion pre-compensation

We present a high-speed wavelength tunable photonic crystal fiber-based source capable of generating tunable femtosecond solitons in the infrared region. Through measurements and numerical simulation, we show that both the pulsewidth and the spectral width of the output pulses remain nearly constant over the entire tuning range from 860 to 1160 nm. This remarkable behavior is observed even when pump pulses are heavily chirped (7400 fs^2), which allows to avoid bulky compensation optics, or the use of another fiber, for dispersion compensation usually required by the tuning device.Comment: 8 pages, 11 figure

Optimum integration procedures for supercontinuum simulation

We study numerical solutions of the generalized nonlinear Schro¨ dinger equation (GNLSE), focusing on the advantage of integrating the nonlinear part of the equation in the frequency domain (FD), rather than in the time domain (TD), when simulating supercontinuum generation in optical fibers. We show that integration of the nonlinear operator in the FD is more efficient than its integration in the TD. We analyze different adaptive stepsize algorithms in combination with the interaction picture integration method and show that their performance strongly depends on whether integration of the nonlinear operator is performed in the FD or TD. We find that the most efficient procedure for supercontinuum simulation in optical fibers results from solving the nonlinearity in the FD and applying the recently introduced conservation quantity error adaptive step-size algorithm.Fil: Rieznik, Andrés Anibal. Instituto Tecnológico de Buenos Aires. Departamento de Investigación y Doctorado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Heidt, A. M.. University of Stellenbosch; Sudáfrica. Leibniz Institute of Photonic Technology; AlemaniaFil: König, Pablo Germán. Instituto Tecnológico de Buenos Aires. Departamento de Investigación y Doctorado; ArgentinaFil: Bettachini, Victor. Instituto Tecnológico de Buenos Aires. Departamento de Investigación y Doctorado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Grosz, Diego Fernando. Instituto Tecnológico de Buenos Aires. Departamento de Investigación y Doctorado; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Arithmetic on Your Phone: A Large Scale Investigation of Simple Additions and Multiplications

We present the results of a gamified mobile device arithmetic application which allowed us to collect vast amount of data in simple arithmetic operations. Our results confirm and replicate, on a large sample, six of the main principles derived in a long tradition of investigation: size effect, tie effect, size-tie interaction effect, five-effect, RTs and error rates correlation effect, and most common error effect. Our dataset allowed us to perform a robust analysis of order effects for each individual problem, for which there is controversy both in experimental findings and in the predictions of theoretical models. For addition problems, the order effect was dominated by a max-then-min structure (i.e 7+4 is easier than 4+7). This result is predicted by models in which additions are performed as a translation starting from the first addend, with a distance given by the second addend. In multiplication, we observed a dominance of two effects: (1) a max-then-min pattern that can be accounted by the fact that it is easier to perform fewer additions of the largest number (i.e. 8�3 is easier to compute as 8+8+8 than as 3+3+⋯+3) and (2) a phonological effect by which problems for which there is a rhyme (i.e. "seis por cuatro es veinticuatro") are performed faster. Above and beyond these results, our study bares an important practical conclusion, as proof of concept, that participants can be motivated to perform substantial arithmetic training simply by presenting it in a gamified format.Fil: Zimmerman, Federico Guido. Universidad de Buenos Aires; Argentina. Universidad Torcuato Di Tella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Shalóm, Diego Edgar. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Gonzalez, Pablo A.. No especifíca;Fil: Garrido, Juan Manuel. No especifíca;Fil: Alvarez Heduan, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dehaene, Stanislas. Inserm; FranciaFil: Sigman, Mariano. Universidad Torcuato Di Tella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rieznik, Andrés Anibal. Universidad Torcuato Di Tella; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A massive experiment on choice blindness in political decisions : confidence, confabulation, and unconscious detection of self-deception

We implemented a Choice Blindness Paradigm containing political statements in Argentina to reveal the existence of categorical ranges of introspective reports, identified by confidence and agreement levels, separating easy from very hard to manipulate decisions. CBP was implemented in both live and web-based forms. Importantly, and contrary to what was observed in Sweden, we did not observe changes in voting intentions. Also, confidence levels in the manipulated replies where significantly lower than in non-manipulated cases even in undetected manipulations. We name this phenomenon unconscious detection of selfdeception. Results also show that females are more difficult to manipulate than men.Fil: Rieznik, Andrés. Universidad Torcuato Di Tella, Escuela de Negocios, Laboratorio de Neurociencia, Buenos Aires, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina. El Gato y La Caja, Buenos Aires, Argentina.Fil: Moscovich, Lorena. Universidad de San Andrés, Buenos Aires, ArgentinaFil: Frieiro, Alan. Universidad de Vigo, Vigo, EspañaFil: Figini, Julieta. Universidad de San Andrés, Buenos Aires, ArgentinaFil: Catalano, Rodrigo. El Gato y La Caja, Buenos Aires, ArgentinaFil: Garrido, Juan Manuel. El Gato y La Caja, Buenos Aires, ArgentinaFil: Álvarez Heduan, Facundo. El Gato y La Caja, Buenos Aires, ArgentinaFil: Sigman, Mariano. CONICET, Buenos Aires, Argentina. Universidad Torcuato Di Tella, Escuela de Negocios, Laboratorio de Neurociencia, Buenos Aires, ArgentinaFil: González, Pablo A. El Gato y La Caja, Buenos Aires, Argentin

Mora: matemática para jugar : Una experiencia de ciencia colectiva

La intención final con Mora es lograr, a la vez, un juego para entrenamiento de habilidades matemáticas y una herramienta de investigación que, a través de un proceso de ciencia colectiva, permita identificar marcadores asociados a discalculia. Los objetivos específicos de esta primera etapa de implementación fueron motivar a niños y niñas en la práctica de las habilidades de aritmética y analizar cómo influye el entrenamiento de dichas habilidades en el tiempo de respuesta y el porcentaje de aciertos.Facultad de Informátic