Variable Optical Attenuator Using Active Multimode Interference Waveguide

We propose a new structure for an integrated variable optical attenuator using InGaAsP multiple quantum wells. The principle of operation relies on the self-imaging properties of multimode interference (MMI) waveguides. The device consists of a MMI region that is 12 μm wide by 350 μm long, with input and output waveguides that are 2 μm wide. The dimensions of the MMI are calculated such that an image of the input field is produced at the output waveguide. The last statement is true as long as the phase relation between the modes in the MMI section is kept constant. Therefore, by selectively perturbing the refractive index within the MMI section, the phase relation of the modes is altered, thereby modifying the interference properties at the output of the device. We present numerical simulations using the Finite-Difference Beam Propagation Method (FD-BPM), and demonstrate that optical attenuation is possible by selectively modulating the refractive index of a narrow region within the MMI section. A dynamic range of -37 dB can be easily obtained at a wavelength of 1.55 μm with a device insertion loss of 0.3 dB. The effects of electro-absorption on the device performance are also investigated

Effects Of Out-Coupling In Fiber Lasers

An analysis of out-coupling in a laser shows an optimum way of subtracting more output power by choosing an appropriate cavity arrangement from a high-power fiber laser. This investigation consisted in resolving analytically the effect of different cavities in our laser system and one thing that outcome was to know that a fiber laser can operate with high efficiency even with high losses in one end of the cavity (e.g. at an external diffraction grating), only if the feedback in the out-coupling end is low. Moreover, it was also found that is possible to improve the output power by reducing the feedback in the out-coupling end. Parameters considered in this resolved method are 0.1 NA, 10 μm diameter core, 200 μm inner-cladding diameter and 10 dB small-signal absorption. The fiber laser was doped with ytterbium and lases at 1080 nm, when pumped at 915 nm. The maximum pump power was set to 10 W

Diseño, fabricación y prueba de una antena de parche para GPS en aplicaciones automotrices Diseño, fabricación y prueba de una antena de parche para GPS en aplicaciones automotrices

This work is focused on the development of a prototype patch antenna designed for use asa replacement antenna in automotive Global Positioning Systems (GPS). In simulations andtesting of the prototype, the focus was on the antenna gain. Transmission-reception testingwas done to verify the operation frequency. The prototype was tested with a commercial GPSkit to evaluate its performance as a replacement antenna. Laboratory testing showed that itcomplied with the minimum requirements for both reception and transmission frequencies,while testing on a stationary vehicle showed slight variations when compared to the positiondata obtained using the same kit with its original antenna. In non-stationary testing, positiondeterminations made with the prototype were sufficiently precise for use.Este trabajo se centra en el desarrollo de una antena de parche diseñada para Sistemas de Posicionamiento Global (GPS), con la finalidad de emplearla como antena de reemplazo en aplicaciones automotrices. En las simulaciones y pruebas se pone énfasis en su ganancia. Las pruebas de transmisión-recepción se realizaron para verificar que la frecuencia de operación de la antena fabricada sea la adecuada. Las pruebas con un kit de GPS comercial fueron realizadas para comparar su desempeño como antena de reemplazo. Las pruebas de laboratorio muestran que se cumple con el mínimo requerido para cubrir ambas frecuencias, de recepción y de transmisión, mientras que las pruebas del prototipo, en el techo vehículo sin movimiento, mostraron ligeras variaciones en los datos de posición, comparados con los obtenidos con el kit con su antena original. Las pruebas de viaje mostraron la suficiente precisión en la determinación de la posición para su uso.</p

Biestability, Chirping And Switching In A Cuasilineal Photonic Crystal

We present a study of the bistability, switching and chirping in a one dimensional stack (1D photonic crystal) for a linear-nonlinear and both nonlinear media. © 2006 Optical Society of America

Evidence for protection of targeted reef fish on the largest marine reserve in the Caribbean

Metallic nanoparticles, of a few nanometers radii, show nonlinearities that are the object of experimental and theoretical studies, in particular in the framework of composites. A quantum mechanical analysis of such structures predict a Kerr type nonlinearity, however quite a recent publication on a classical approach has shown that a classical metallic nanoparticles composite shows a nonlinearity proportional to the electric field amplitude, not to the intensity as is in the Kerr case. The capability of filling up the core of a piece fiber with such composites open the possibility of preparing long enough pieces of fiber with such a composite as well as the straightforward drawing of a fiber doped with nanoparticles. In this work we carry on the numerical simulation on such class of fibers, with the specific aim of looking at the corresponding soliton propagation in an optical fiber with a core doped metal nanoparticles. " 2009 SPIE.",,,,,,"10.1117/12.839854",,,"http://hdl.handle.net/20.500.12104/43204","http://www.scopus.com/inward/record.url?eid=2-s2.0-70449557114&partnerID=40&md5=7e41b05555b5e864d0bc6a2fc045628d",,,,,,,,"Proceedings of SPIE - The International Society for Optical Engineering",,,,"7386",,"Scopus",,,,,,,,,,,,"Nonlinear pulse propagation in an optical fiber doped with conducting nano-particles",,"Conference Paper" "43140","123456789/35008",,"Pina-Amargós, F., Centro de Investigaciones de Ecosistemas Costeros, Cayo Coco, Morán, Ciego de Ávila, Cuba; González-Sansín, G., Department of Studies for Sustainable Development of the Coastal Zone, University of Guadalajara, Jalisco, Mexico; Martín-Blanco, F., Florida Fish andWildlife Conservation Commission, Fish and Wildlife Research Institute, Tequesta, FL, United States; Valdivia, A., Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States",,"Pina-Amargos, F

Study of a spherical photonic crystal with conducting nano shell and a nano particle core

We discuss the effects of a 3D Metallo Dielectric Photonic Crystal with both a metallic core and a metallic shell as basic elements. We discuss the formed cavity as well as the dielectric stack in a structured sphere. © 2010 Optical Society of America

Nonlinear quantum wires

We discuss, numerically and analytically, the nonlinear modes and supermodes of nonlinear Quantum wires. In particular a nonlinearity Kerr type In, where I is the intensity, and the Kerr elliptic solutions characterized by integral constants. © 2010 Optical Society of America