2003
Authors
Melo, M; Frazao, O; Romero, R; Andre, PS; Marques, PVS; Salgado, HM; Santos, JL;
Publication
PROCEEDINGS OF THE INTERNATIONAL 2003 SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE - IMOC 2003, VOLS I AND II
Abstract
In this paper we present and evaluate the spectral response of uniform gratings written in different tapered core sections of single mode fibre. This combination of uniform gratings and tapers leads to three, types of Chirped Fibre Bragg Gratings with different reflection spectra and different mechanical properties. These devices are characterized in function of the applied strain, showing interesting chirp tunability.
2004
Authors
Romero, R; Frazao, O; Floreani, F; Zhang, L; Marques, PVS; Salgado, HM;
Publication
Proceedings of the IASTED International Conference Communication Systems and Networks
Abstract
A multiplexer/demultiplexer for 100 GHz channel spacing based on chirped fibre Bragg gratings with different bandwidths and optical circulators is presented. The spectral characteristics, specifications and operation of these passive devices are described, showing its potential use in DWDM applications.
2002
Authors
Melo, M; Teixeira, A; Frazao, O; Gomes, L; Lima, M; Santos, C; Pereira, D; Rocha, F; Salgado, HM;
Publication
2002 IEEE/LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2
Abstract
We present and demonstrate a 20 nm tunable L-band fiber ring laser. Tunability is achieved by curving a simple taper which controls the intra-cavity loss.
2001
Authors
Frazao, O; Rego, G; Lima, M; Teixeira, A; Araujo, FM; Andre, P; da Rocha, JF; Salgado, HM;
Publication
LONDON COMMUNICATIONS SYMPOSIUM 2001, PROCEEDINGS
Abstract
We have flattened the gain spectrum of a commercial Erbium-doped fibre amplifier, obtaining a curve with approximately 3 dB of ripple, from 1524 nm to 1551 nm, using long-period fibre gratings as equalising optical filters. The fabrication principle of the long-period fibre grating is based on the electric arc technique.
2024
Authors
Elsaid, M; Inácio, I; Salgado, M; Pessoa, M;
Publication
Proceedings of the International Conference on Electromagnetics in Advanced Applications, ICEAA
Abstract
The Sub-THz and millimeter-wave bands have gained popularity, with the expectation that they will host the next generation of wireless communication systems. Furthermore, research on beam-steering characteristics provided by Programmable Electromagnetic Surfaces, such as Reflective Intelligent Surfaces (RISs), has garnered considerable attention as an enabling technology for 6G communications. Due to size limitations, RISs face challenges related to power consumption in the reconfigurable elements and their integration with unit cells operating at high frequencies. This paper discusses the design of a 1-bit reconfigurable unit cell at the D-band using non-volatile technology to minimize static power consumption. Simulation results show that the proposed unit cell performs well with a reflection loss of less than 1.3 dB in both reconfigurable states across a frequency band from 120 to 170 GHz. Moreover, the phase difference between the two states is maintained at 180? ± 20?, with an operational bandwidth of approximately 16 GHz. The beamforming capabilities, with steering angles from -60? to 60?, of the 12×12 RIS, utilizing the proposed unit cell, have been demonstrated in terms of controlling the main beam radiation precisely to various angles with consistent performance at frequencies of 147 GHz, 152 GHz, and 152.5 GHz. © 2024 IEEE.
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