CTM - Indexed Articles in Journals

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Browsing CTM - Indexed Articles in Journals by Author "296"
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    Misalignment-Resilient Propagation Model for Underwater Optical Wireless Links
    ( 2023) João Henrique Araújo ; Joana Santos Tavares ; Marques,VM ; Henrique Salgado ; Luís Manuel Pessoa ; 296 ; 4760 ; 5686 ; 7658
    This paper proposes a multiple-lens receiver scheme to increase the misalignment tolerance of an underwater optical wireless communications link between an autonomous underwater vehicle (AUV) and a sensor plane. An accurate model of photon propagation based on the Monte Carlo simulation is presented which accounts for the lens(es) photon refraction at the sensor interface and angular misalignment between the emitter and receiver. The results show that the ideal divergence of the beam of the emitter is around 15° for a 1 m transmission length, increasing to 22° for a shorter distance of 0.5 m but being independent of the water turbidity. In addition, it is concluded that a seven-lense scheme is approximately three times more tolerant to offset than a single lens. A random forest machine learning algorithm is also assessed for its suitability to estimate the offset and angle of the AUV in relation to the fixed sensor, based on the power distribution of each lens, in real time. The algorithm is able to estimate the offset and angular misalignment with a mean square error of 5 mm (6 mm) and 0.157 rad (0.174 rad) for a distance between the transmitter and receiver of 1 m and 0.5 m, respectively.
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    Optical direct intensity modulation of a 79GHz resonant tunneling diode-photodetector oscillator
    ( 2019) Zhang,WK ; Kelly,AE ; Wasige,E ; Henrique Salgado ; Al Khalidi,A ; Luís Manuel Pessoa ; Joana Santos Tavares ; Cantu,HI ; Wang,J ; Figueiredo,J ; Watson,S ; 296 ; 5686 ; 4760
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    Resonant tunneling diode photodetectors for optical communications
    ( 2019) Watson,S ; Kelly,A ; Luís Manuel Pessoa ; Henrique Salgado ; Wasige,E ; Wang,J ; Cantu,H ; Figueiredo,J ; Joana Santos Tavares ; Zhang,WK ; 4760 ; 296 ; 5686
    Optical modulation characteristics of resonant tunneling diode photodetectors (RTD-PD) are investigated. Intensity modulated light excites the RTD-PDs to conduct data experiments. Simple and complex data patterns are used with results showing data rates up to 80 and 200 Mbit/s, respectively. This is the first demonstration of complex modulation using resonant tunneling diodes. © 2019 The Authors. Microwave and Optical Technology Letters published by Wiley Periodicals, Inc.