Laureano A. Bulus Rossini

Efectos de backscattering, dispersión, coherencia y ruido en un sistema de monitoreo de redes PON

The application of optical coding as a complement to an OTDR (Optical Time Domain Reflectometer) represents a solution to the problem of the ambiguity occurred in the remote monitoring of optical branched networks. In this work, we evaluate the performance of a monitoring system based on this premise in terms of the OTDR source and receiver characteristics. We evaluate the effects of the monitoring pulse and link characteristics on the interference. We derive restrictions for the minimum pulse width in terms of coherence and dispersion effects. Finally, we study the effect of the receiver noise on the correct detection of codes.

Design and performance evalauation of an optical coding scheme for PON monitoring

Optical coding has numerous properties that make its application to remote monitoring and failure detection in passive optical networks very attractive. Several approaches for encoder implementation have been proposed. One of them consist of a couple of fiber Bragg gratings forming a cavity producing multi-level periodic codes. In this work we propose and evaluate the performance of two new encoder schemes based on this premise. These new encoders generate codes with Hamming weight 2 and 3 in order to improve the performance of multi-level periodic codes. We observe that the proposed coding schemes show a better performance under certain scenarios.

False Detections in an Optical Coding-Based PON Monitoring Scheme

We address the issue of false detections in an optical coding-based PON monitoring scheme. An analytical expression for the average number of false detections is derived and the system performance in terms of false detections is evaluated. We show that a feasible, low-cost scheme can monitor a large number of users with less than one false detection per user even in high-density PONs.

Control Strategy of True Time Delay Lines

ABSTRACT This article presents the control of adjustable true time delays applied to an optical beamforming system. First is introduced the response of ring resonators of two and four ports and the cascade and lattice structures. The coupling factor and the phase modulation are employed as the control parameters for the adjustable group delay. The strategy of control is proposed and applied to a cascade of five ring resonators for producing wideband true time delays in the picosecond–nanosecond range with 2-GHz bandwidth and extremely low ripple. Ripples lower than 0.1% were obtained for the adjusted group delays. The proposed strategy can be simply extended if more resonators are added to increase the bandwidth of the system.

Diseño y medición de una antena espiral logarítmico para aplicaciones de UWB

This paper describes the fabrication of a matched logarithmic spiral antenna for ultrawideband (UWB) applications able to operate in a frequency band of 1 GHz to 10 GHz. Based on the antenna simulation results, in particular its input impedance, a matching network model was performed in order to achieve at the same time the transformation of a balanced to unbalanced system (balun), a return loss greater than 10 dB and an input impedance of 50 Ω. Finally, the simulated data of the antenna - adapter integration and the measurement results were compared, for which a great degree of accordance was found.

Estimation of non-linear effects in optical fiber systems based on perturbation models

In this paper we introduce an estimation model of the non-linear effects which affect the signal propagating through optical fiber communication systems with wavelength division multiplexing (WDM). The emergence of non-linear effects with the increase of the transmitted power represents a fundamental limit in current high capacity communication systems. Previously proposed models based in perturbation theory such as the Gaussian Noise model (GN) consider the non-linear interference as additive Gaussian noise. We compare the model estimation results with those obtained through simulation of the optical fiber system by means of extensively verified algorithms based on the integration of the Non-Linear Schroedinger Equation (NLSE) and the Manakov Equation (ME).

Optimization of the control of dispersion and nonlinear effects in WDM communication systems

A method to compensate linear and nonlinear effects in a high capacity fiber-optic (FO) communication systems, called Distance Folded Digital Backward Propagation (DF or DF-DBP), is implemented. It is a variant of the Digital Backward Propagation method (DBP) and it has the advantage of reducing the computational cost with respect to DBP. The DF consists in applying the Split Step Fourier Method (SSFM) to solve the nonlinear Schrödinger equation (NLSE) conversely, but using fewer steps than in the DBP. It is evaluated a DF implementation for an 8-channel division multiplexed wavelength (WDM) system, with a transmission rate of 128 Gb/s per channel, a 16-QAM modulation format, and a link of 1200 km length. The system performance is compared in three cases: when electronic compensation is used by DF and by DBP, and when optical dispersion compensation is employed through DCF fiber.

Control de efectos no lineales y dispersión en sistema WDM de Comunicaciones Ópticas

This paper presents a study of a method called Digital Backward Propagation (DBP) to compensate, simultaneously, the linear and nonlinear effects that occur in a communication link of 10 Gb/s over 500 km of optical fiber (FO), with 8 wavelength division multiplexed (WDM) channels. The procedure used consists in applying the Split Step Fourier Method (SSFM) to solve the inverse Nonlinear Schrödinger Equation (NLSE) by using digital signal processing (DSP) techniques with no inline compensation. The modulation format used for transmission is 4-QAM (Quadrature Amplitude Modulation). The DBP compensation system is compared with a system without compensation and with a link in which only the chromatic dispersion is compensated by dispersion compensated fibers (DCF).

Sintonización de líneas de retardo de banda ancha basadas en ORRs

This paper presents a method to control the delays generated by a cascade of optical ring resonators (ORRs). Delays generated were implemented numerically using 5 ORRs of 12 mm diameter, embedded in silicon dioxide (SiO2) and silicon nitride (Si3N4), and their values were approximately constant in a bandwidth near to 3 GHz. The control parameters of the system are given by the coupling factor and the phase shift of each ORR.

Adaptador de impedancias para antenas de 9 GHz de ancho de banda

This paper describes the design and analysis of an impedance matching network for spiral logarithmic (self-complementary) broadband antennas, able to operate in a frequency band of 1 GHz to 9 GHz. The proposed design is based on tapered microstrip lines which exhibit a progressive variation of its width by obtaining a gradual change in the impedance. Employing similar concepts over the ground plane, the transformation of a balanced to unbalanced system is achieved (Microstrip to Parallel Striplines Balun), which is necessary to connect the antenna to its feed. This design was optimized for low return loss and unity power transfer. The design was validated by simulation, yielding a return loss greater than 10 dB and an impedance matching between 50 Ω and 188 Ω, throughout the frequency range of interest.