1,721,017 research outputs found
Time-variant signal encryption by lensless dual random phase encoding applied to fiber optic links
No full textA lensless dual random phase encoding technique in the temporal domain is proposed and analyzed to evaluate its potential application for secure data transmission, mainly for short-haul fiber optic links. The different signal broadening effects produced by each stage of the encoding process in both time and frequency domains are analyzed by using the Wigner distribution function to take into account the fiber’s multiplexing capabilities. Thus, quasi-white noise with a well-defined bandwidth is used in the encoding process to limit the bandwidth of the encrypted signal. Numerical simulations revealed good system performance, indicating that this multiplexing encryption method could be a good alternative to other well-established techniques.Fil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentin
Mechanochemical Reactions in Fe2O3–M (M: Al, Ti)
Get PDFThe production of metal–ceramic nanodispersion by mechanical milling of powders through the displacement reaction Fe2O3+M→Fe+M-oxide (with M: Al, Ti) was studied. The reaction progress with milling time was followed by recording the temperature and pressure during the process. The samples were characterized by X-ray diffraction and Mössbauer spectroscopy at the intermediate and final stages. In both cases self-sustained reactions were observed with different activation times. The results confirm that mechanical work at room temperature yields the reduction of hematite by Ti and Al. The final oxides were identified as Ti2O3 and Al2O3, respectively. The dependence of the intermediate and final stages on the milling conditions and the starting composition will be discussed.Fil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Damonte, Laura Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Mendoza Zélis, Luis Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentin
Joint transform correlator optical encryption system: Extensions of the recorded encrypted signal and its inverse Fourier transform
Get PDFIn this work we study the joint transform correlator setup, finding two analytical expressions for the extensions of the joint power spectrum and its inverse Fourier transform. We found that an optimum efficiency is reached, when the bandwidth of the key code is equal to the sum of the bandwidths of the image plus the random phase mask (RPM). The quality of the decryption is also affected by the ratio between the bandwidths of the RPM and the input image, being better as this ratio increases. In addition, the effect on the decrypted image when the detection area is lower than the encrypted signal extension was analyzed. We illustrate these results through several numerical examples.Fil: Galizzi, Gustavo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina. Universidad Catolica Argentina; Argentin
Time-Variant Signal Encryption by Dual Random Phase Encoding Setups Applied to Fiber Optics Links
No full textSpatial optical techniques have shown great potential in the field of information security to encode high-security images. Among them, the dual random phase encoding method (DRPE) has received much attention, since it was proposed by Réfrégier and Javidi at the middle 1990s. Since then, a number of works in the field were proposed introducing different variations of this technique. On the other hand, the space-time duality refers to the close mathematical analogy that exists between the equations describing the paraxial diffraction of beams in space and the first-order temporal dispersion of optical pulses in dielectric media. It is generally used for extending to the temporal domain well-known properties of spatial optical configurations. In this work it is developed a new approach to the secure data transmission problem in fiber optic links. We propose the encoding of time-varying optical signals, mainly for short-haul applications, with encryption methods that can be considered the time domain counterparts of the DRPE, and two of its more frequent variations: the fractional Fourier transform DRPE and the Fresnel transform encoding. Further, as performance is a very relevant subject in fiber optic links, we will analyze mechanisms to produce time limited, as well as bandwidth limited, encoded signals. To this end, the different signal broadenings produced by each stage of the encoding process in both, time and frequency domains, are analyzed by using the Wigner distribution function formalism, and general expressions for the time width, as well as the bandwidth, at all encryption stages are obtained. The numerical simulations show the good system performances, and a comparison between the different encryption processes is made. Furthermore, the robustness of the proposed methods is analyzed against the variation of typical parameters of the encryption-decryption setup. Finally, the implementation of this proposal with current photonic technology is discussed.Fil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; Argentin
Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator
Get PDFWe demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power.Fil: Cuadrado Laborde, Christian Ariel. Universidad de Valencia; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Catolica de La Plata; ArgentinaFil: Bello Jiménez, M.. Universidad de Valencia; España. Universidad Autónoma de San Luis Potosí; MéxicoFil: Diez, A.. Universidad de Valencia; EspañaFil: Cruz, J. L.. Universidad de Valencia; EspañaFil: Andrés, M. V.. Universidad de Valencia; Españ
Wavelength-division multiplexing Fresnel transform encoding of time-varying signals
No full textWe study the wavelength-division multiplexing implementation of the recently proposed temporal Fresnel transform encoding technique, in order to evaluate its potential application for secure data transmission in short-haul fiber optic links. The different signal broadenings produced by each stage of the encoding process are analyzed in a dual time-frequency domain by using the Wigner distribution function. Furthermore, the robustness of the proposed method is illustrated by comparing the signal-to-noise ratio between the input and the decrypted signals obtained by varying typical parameters of the encryption-decryption setup. Numerical simulations revealed good system performance. Finally, we consider experimental feasibility with current photonic technology.Fil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Duchowicz, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Sicre, Enrique Eduardo. Universidad Argentina de la Empresa. Facultad de Ingeniería y Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Nonlinearity measurement undergoing dispersion and loss
No full textAccurate knowledge of the nonlinear coefficient is extremely important to make reliable predictions about optical pulses propagating along waveguides. Nevertheless, determining this parameter when dispersion and loss are as important as nonlinear effects brings both theoretical and experimental challenges that have not yet been solved. A general method for measuring the nonlinear coefficient of waveguides under these demanding conditions is here derived and demonstrated experimentally in a kilometer-long standard silica fiber pumped close to 2 μm.Fil: Castelló Lurbe, David. Universidad de Valencia; España. Vrije Unviversiteit Brussel; BélgicaFil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Silvestre, Enrique. Universidad de Valencia; EspañaFil: Díez, Antonio. Universidad de Valencia; EspañaFil: Andrés, Miguel V.. Universidad de Valencia; Españ
Sub-picosecond ultra-low frequency passively mode-locked fiber laser
Get PDFWe developed a nonlinear polarization rotation all-fiber mode-locked erbium-doped fiber laser, with the purpose to reach a sub-picosecond and sub-megahertz light pulse emission. In the process, we observed three different emission regimes as the net birefringence is changed, namely high-power dissipative soliton resonance, low-power soliton regime, and a mixed combination of both. In the pure solitonic regime, a 0.961 MHz train of chirp-free Gaussian pulses was obtained, with a time width of 0.919 ps at 1564.3 nm.Fil: Cuadrado Laborde, Christian Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; Argentina. Universidad de Valencia; EspañaFil: Cruz, José L.. Universidad de Valencia; EspañaFil: Diez, Juan Antonio. Universidad de Valencia; EspañaFil: Andrés, Miguel V.. Universidad de Valencia; Españ
Photonic fractional Fourier transformer with a single dispersive device
Get PDFIn this work we used the temporal analog of spatial Fresnel diffraction to design a temporal fractional Fourier transformer with a single dispersive device, in this way avoiding the use of quadratic phase modulators. We demonstrate that a single dispersive passive device inherently provides the fractional Fourier transform of an incident optical pulse. The relationships linking the fractional Fourier transform order and scaling factor with the dispersion parameters are derived. We first provide some numerical results in order to prove the validity of our proposal, using a fiber Bragg grating as the dispersive device. Next, we experimentally demonstrate the feasibility of this proposal by using a spool of a standard optical fiber as the dispersive device.Fil: Cuadrado Laborde, Christian Ariel. Consejo Superior de Investigaciones Cientificas. Instituto de Ciencia de Los Materiales de Barcelona; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Universidad Catolica de La Plata; ArgentinaFil: Carrascosa, A.. Consejo Superior de Investigaciones Cientificas. Instituto de Ciencia de Los Materiales de Barcelona; EspañaFil: Diez, Antonio. Consejo Superior de Investigaciones Cientificas. Instituto de Ciencia de Los Materiales de Barcelona; EspañaFil: Cruz, Jose Luis. Consejo Superior de Investigaciones Cientificas. Instituto de Ciencia de Los Materiales de Barcelona; EspañaFil: Andres Bou, Miguel. Consejo Superior de Investigaciones Cientificas. Instituto de Ciencia de Los Materiales de Barcelona; Españ
Instantaneous frequency measurement of dissipative soliton resonant light pulses
Get PDFWe measured the instantaneous frequency profile of two different dissipative soliton resonant (DSR) light pulses, the usual flat-top and less-common trapezoid-shaped light pulses. The DSR light pulses were provided by an ytterbiumdoped polarization-maintaining fiber ring passively modelocked laser using the adequately selected amount of net-normal dispersion. We confirmed that the DSR light pulses have a (moderately) low linear chirp across the pulse, except at the edges, where the chirp changes exponentially. This unique instantaneous frequency behavior can be succinctly resumed by the following parameters: linear chirp slope and leading and trailing chirp lifetimes. As the pump power increases, the linear chirp slope decreases, whereas the leading and trailing chirp lifetimes do not show an appreciable change. The results are compared with previous theoretical works.Fil: Cuadrado Laborde, Christian Ariel. Universidad de Valencia; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentina. Universidad Catolica Argentina; ArgentinaFil: Armas Rivera, I.. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Carrascosa, A.. Universidad de Valencia; EspañaFil: Kuzin, E. A.. INAOE; MéxicoFil: Beltrán Pérez, G.. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Díez, A.. Universidad de Valencia; EspañaFil: Andrés, M. V.. Universidad de Valencia; Españ
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