Luis Carvalho

Towards software defined autonomic terabit optical networks

This paper presents an Optical SDN architecture and implementation enabled for virtual optical networks, supporting adaptive and cognitive algorithms to enhance QoT. The paper also shows experimental results of a software-defined autonomic flexible transponder.

Toward terabit autonomic optical networks based on a software defined adaptive/cognitive approach [invited]

Terabit elastic optical networking (EON) is foreseen as a viable solution to extend the lifetime of a network exploiting the available bandwidth in previously deployed optical fibers. EON is based on bandwidth-variable transponders capable of supporting multiple bit rates and/ or modulation formats according to traffic requirements and node architectures that route arbitrary channel band-widths. Thus, EON increases the heterogeneity of the network, which may create the need for autonomie adaptive and/or cognitive techniques. In this context, the software-defined networking (SDN) paradigm emerges as an opportunity to enable such techniques thanks to the centralized view of the network by decoupling the control plane and the data plane. This paper surveys different activities carried out at the Optical Technologies Division in Centro de Pesquisa e Desenvolvimento em Telecomunicações, Brazil. We review an optical transport SDN controller for virtual optical networks that supports two adaptive algorithms. First, the autonomie flexible transponder reconfigures the transmission modulation format according to a threshold level. Second, the adaptive global spectrum equalization reconfigures the wavelengths attenuation profiles applied at the optical nodes to improve the signals optical signal-to-noise ratio (OSNR) at reception. Finally, we report experimental results of an in-band OSNR monitor for advanced modulation formats.

A Lyapunov Functional for a Retarded Differential Equation

Consider the autonomous linear retarded differential equation [dot x(t) = A_0 x(t) + A_1 x(t - r) + int_{ - r}^0 {A_{01} (theta )x(t + theta )dtheta .} ] A positive definite quadratic functional is given that yields an equivalent norm in the phase space, which measures the exact asymptotic behavior of its solutions, providing the best estimate for the rate of growth or decay of the said solutions.

Desenvolvimento e resultados preliminares de um sistema cromático de iluminação para oftalmoscópios indiretos

PURPOSE: Chromatic contrast is a technique used in some areas of medicine to provide better visualization of biological tissues. Based on principles of color composition, a new illumination system was constructed using colored emitting diodes to reproduce the spectral range of visible light. This technique was devised to be used in indirect ophthalmoscopes to improve the visualization of the posterior segment of the eye. METHODS: The original illumination system of a general purpose indirect ophthalmoscope was substituted by a system of color-emitting diodes. RESULTS: Using an electronic interface it was possible to control the intensity of the color lights and therefore generate different wavelengths in the visible spectrum of the light. Preliminary tests undertaken in a mechanical model of the human eye generated very clear and homogenous colors. However in vivo examinations with patients were performed in our laboratory at the IFSC-USP and UNIFESP, and obtained the preliminary results show the possibilities of the chromatic contrast technique, and may represent in the future a differential in the analyses of the posterior segment of the eye. CONCLUSION: The use of color-emitting diodes to reproduce the spectral range of the visible light in indirect ophthalmoscopes seems to be a promising technological advance in the fundoscopy of the eye. This is an innovation that can yield better quality examinations with indirect ophthalmoscopes.

Generation and Coherent Detection of a 400-Gb/s CO-OFDM Superchannel with 6.4-b/s/Hz

The generation and coherent detection of a 400-Gb/s CO-OFDM superchannel (4x100-Gb/s PDM-16QAM), with 6.4-b/s/Hz spectral efficiency is presented. A required OSNR of 22.9 dB at the threshold BER of 3.8x10-3 (7% HD-FEC overhead) was obtained.

Resultados preliminares de um sistema computadorizado e estereoscópico para pupilometria in vivo

OBJETIVOS: Desenvolver um sistema digital, com capacidade de induzir acomodacao, para medida do diâmetro e formato da pupila para dez diferentes niveis de iluminacao (LUX), variando do nivel mesopico ao fotopico. METODOS: Um sistema optico para conjugar imagens da pupila iluminada por LED infravermelho e branco foi projetado e montado usando um capacete tipico de oftalmoscopio e uma mascara tipica de mergulhador como suporte e uma câmera CCD de alta resolucao e sensibilidade. Algoritmos usando principios de processamento de imagens foram implementados para leitura do arquivo de video e a deteccao automatica do centro geometrico e diâmetro da pupila para cada quadro. RESULTADOS: Apresentamos dados preliminares deste sistema para um paciente voluntario. Os dados sobre posicao horizontal (x), vertical (y) do centro geometrico e do diâmetro da pupila foram exportados para arquivos texto que podem ser impressos usando um programa convencional de planilha (Excel). O processo de acomodacao e garantido por uma mira virtual (LED branco) localizada a 6 metros do olho do paciente e o nivel de iluminacao e precisamente controlado por uma placa eletronica que alimenta o LED central que tem sua potencia controlada pelo software. CONCLUSOES: Com o instrumento desenvolvido dados precisos da posicao e tamanhos da pupila podem entao ser obtidos estereoscopicamente (para ambas as pupilas e ao mesmo tempo) para qualquer paciente. Acreditamos que tal instrumento possa ser util em algumas praticas oftalmicas onde as caracteristicas geometricas da pupila sejam importantes.