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Publicações

Publicações por Henrique Salgado

2009

Characterization of semiconductor lasers for radiation hard high speed transceivers

Autores
Silva, S; Amara, LS; Detraz, S; Moreira, P; Papadopoulos, S; Papakonstantinou, I; Salgado, HM; Sigaud, C; Soos, C; Stejskal, P; Troska, J; Vasey, F;

Publicação
Proceedings of the Topical Workshop on Electronics for Particle Physics, TWEPP 2009

Abstract
In the context of the versatile link project, a set of semiconductor lasers were studied and modelled aiming at the optimization of the laser driver circuit. High frequency measurements of the laser diode devices in terms of reflected and transmission characteristics were made and used to support the development of a model that can be applied to study their input impedance characteristics and light modulation properties. Furthermore the interaction between the laser driver, interconnect network and the laser device itself can be studied using this model. Simulation results will be compared to measured data to validate the model and methodology.

2012

Experimental assessment of WLAN performance supported in a fiber-radio network

Autores
Pessoa, LM; Oliveira, JMB; Coelho, D; Castro, JCS; Salgado, HM;

Publicação
2012 Future Network and Mobile Summit, FutureNetw 2012

Abstract
In this paper we experimentally evaluate the performance of a fiber supported radio application, namely WiFi IEEE802.11n, using a low power consumption base-station based on a reflective electro absorption modulator and commercial transceivers. We conclude that the proposed setup is suitable to achieve a transmission of 20 Mbit/s over a 4m wireless channel. A theoretical signal to noise ratio analysis is also carried out, based on experimental results. Finally, we evaluate the possibility of employing the proposed setup in a passive optical network, concluding that this solution may not be cost effective. © 2012 IIMC Ltd.

2011

Cooperative clustered architecture and resource reservation for OBS networks

Autores
Haq, IU; Salgado, HM; Castro, JCS;

Publicação
International Congress on Ultra Modern Telecommunications and Control Systems and Workshops

Abstract
Resource contention is a major concern in Optical Burst Switching networks that leads to relatively high burst loss probability. This article presents a clustered architecture for OBS networks, called Cooperative Clustered Optical Burst Switching (C2OBS) network architecture. In this architecture, the network is divided in overlapping zones/clusters with a zone/cluster head having the knowledge of available resources within the zone called Zonal Base (ZB) and maintains a short resource usage history called Short History Base (SHB). A resource reservation strategy for the proposed Cooperative Clustered OBS network architecture (C2OBS-RR) is also presented which is centralized within the zone and distributed in the overall network, for combining the benefits of both the centralized and the distributed resource reservation schemes. This novel approach uses the local state of the resource availability within the zone (ZB) so that the bursts originating at the ingress nodes in the same part of network having been assigned the same wavelength, can be assigned different time offsets. This will proactively reduce the probability of contention at the intermediate nodes within a zone and is expected to significantly reduce the overall network burst loss probability. For illustration purpose, the proposed C2OBS architecture has been applied to the European Optical Network. © 2011 HTE.

1996

Experimental validation of Volterra series nonlinear modelling for microwave subcarrier optical systems

Autores
Salgado, HM; O'Reilly, JJ;

Publicação
IEE Proceedings: Optoelectronics

Abstract
A detailed comparative experimental and theoretical study of nonlinear distortion in laser diodes is undertaken to provide practical proving of the effectiveness and utility of the Volterra series method. The observed harmonic and intermodulation distortion levels are compared with the results given by the Volterra series nonlinear laser model using intrinsic parameters extracted from reflection and small-signal frequency response measurements. Second-harmonic, two-tone and three-tone intermodulation distortion data are all found to be in good agreement with the theoretical results, providing endorsement of the Volterra series approach for the study of distortion in microwave subcarrier optical systems. © IEE, 1996.

1995

Cancellation of third-order intermodulation distortion in a directly modulated DFB laser and optical discriminator

Autores
Castro, JCS; Salgado, HM; O'Reilly, JJ; Todd, CJ;

Publicação
Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS

Abstract
This work uses Volterra kernels to model the distortion of complex optical systems using both frequency and intensity modulation of a DFB laser and an optical discriminator. The laser's IM and FM complex responses and also the laser's intrinsic FM distortion are shown to be crucial to model accurately the system's third-order intermodulation product (IMP3) performance. The results show that it is possible to achieve a large reduction of the third-order IMP3 in some frequency ranges by off-setting the bias of the discriminator from the point of maximum slope. Furthermore, at high frequencies the system's IMP3 performance can be better than in the case of a purely intensity modulated laser without a discriminator.

1993

Performance assessment of FM broadcast subcarrier-multiplexed optical systems

Autores
Salgado, HM; O'Reilly, JJ;

Publicação
IEE proceedings. Part J, Optoelectronics

Abstract
The performance of frequency-modulated (FM) subcarrier-multiplexed systems is assessed using Volterra series analysis to model laser nonlinear distortion accurately. The intermodulation-power spectral density and the carrier-to-intermodulation ratio are then determined. The performance of these systems is investigated by considering all noise contributions: intermodulation and relative intensity noise in the transmitter and receiver thermal and shot noise. Optimum performance is also identified. A 62-channel FM video system occupying the bandwidth of 2.7-5.2 GHz provides an illustrative example.

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