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Publications

Publications by CTM

1994

OPTICAL SHOCK-WAVES IN NONLINEAR DISPERSIVE AMPLIFYING MEDIA

Authors
CHRISTODOULIDES, DN; CARVALHO, MI;

Publication
OPTICS LETTERS

Abstract
We show that optical shock-wave solutions are possible in nonlinear dispersive amplifying media that exhibit a frequency-dependent gain and background loss. These shock-wave domains exist at lasing threshold and are permitted in both the normal and the anomalous dispersive regions.

1994

COMPRESSION, SELF-BENDING, AND COLLAPSE OF GAUSSIAN BEAMS IN PHOTOREFRACTIVE CRYSTALS

Authors
CHRISTODOULIDES, DN; CARVALHO, MI;

Publication
OPTICS LETTERS

Abstract
By means of an exact solution, we demonstrate that a Gaussian beam can undergo spatial compression when it traverses a photorefractive medium. This is possible provided that the external bias field exceeds the critical value necessary to establish photorefractive spatial solitons. In this regime and under paraxial assumptions our analysis indicates that a Gaussian beam tends to exhibit self-focusing collapse. Beam self-deflection effects that arise from the pi/2-phase-shifted component of the photorefractive grating are also considered in our study.

1993

CONTROL AND OBSERVATION OF ANALOG NODES IN MIXED-SIGNAL BOARDS

Authors
MATOS, JS; LEAO, AC; FERREIRA, JC;

Publication
INTERNATIONAL TEST CONFERENCE 1993 PROCEEDINGS: DESIGNING, TESTING, AND DIAGNOSTICS - JOIN THEM

Abstract
BST is a well established standard and testability framework for digital ICs and boards. The paper presents a test support IC controlled by an IEEE1149.1 interface, capable of providing access to analog nodes in mixed-signal boards. The proposed architecture (ABSINT - Analog to Boundary Scan Interface) is described and relevant implementation issues are discussed. A demonstrator IC implementing the ABSINT architecture is presented, and it is shown how it can be used to provide analog test channels under control of IEEE1149.1.

1993

Performance assessment of FM broadcast subcarrier-multiplexed optical systems

Authors
Salgado, HM; O'Reilly, JJ;

Publication
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.

1993

RACE R2005: microwave optical duplex antenna link

Authors
O'Reilly, JJ; Lane, PM; Capstick, MH; Salgado, HM; Heidemann, R; Hofstetter, R; Schmuck, H;

Publication
IEE proceedings. Part J, Optoelectronics

Abstract
The paper describes the results to date of the RACE project R2005. The project addresses the optical generation and fibre delivery of mm-wave signals for future mobile radio and remote customer access connections. The authors identify potential application areas and appropriate performance targets for such fibre/mm-wave systems. The major issue identified is the need to achieve low-cost antenna units due to the large number of such units that would be required; this arises from the limited propagation distances achieveable at mm-wave frequencies. A brief review of current optical methods for the generation of mm-waves allows the identification of the inadequacies of these techniques and leads to a description of a new method, developed for the project, that overcomes most of the disadvantages outlined earlier.

1993

Control and Observation of Analog Nodes in Mixed-Signal Boards

Authors
Matos, JS; Leão, AC; Ferreira, JC;

Publication
Proceedings IEEE International Test Conference 1993, Designing, Testing, and Diagnostics - Join Them, Baltimore, Maryland, USA, October 17-21, 1993

Abstract

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