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Bakar A.A.A.,Electronics and System Engineering | Flores J.Z.V.,Queensland University of Technology | Lim Y.L.,Queensland University of Technology | Kliese R.,Queensland University of Technology | Rakic A.D.,Queensland University of Technology
2010 International Conference on Photonics, ICP2010 | Year: 2010

This paper investigates the performance of the Self-Mixing Interferometer (SMI) based on Vertical-Cavity Surface-Emitting Laser (VCSEL) under the influence of polarization mode switching due to optical feedback. The SMI signals are acquired using the variation in junction-voltage of the single mode VCSEL while the optical power in two orthogonal polarizations of the VCSEL fundamental mode are monitored in parallel. Results show that polarization mode switching occurs only at certain laser bias currents and corrupts the SMI signal. © 2010 IEEE. Source


Ab-Rahman M.S.,Electronics and System Engineering | Hassan M.R.,Electronics and System Engineering
IEEE Journal of Quantum Electronics | Year: 2012

In this paper, the authors present a new theory that can be applied to remotely eliminate emitted optical pulse/s. The elimination of the optical pulses can be performed by increasing the threshold carrier density of the laser source during the time period of the injected pulse by exposing the laser diode to an incoherent external optical feedback (EOF) pulse at a specified value of external reflectivity. Consequently, the stimulated emission will not occur and approximately zero photon density will be achieved during the pulse width of the EOF signal. The proposed technique can be utilized to develop a new type of all-optical external encoder. In addition, it can be used to remotely control the laser source and, in turn, the whole optical communication system. © 2006 IEEE. Source


Adam I.,Electronics Section | Mohamed A.,Electronics and System Engineering | Sanusi H.,Electronics and System Engineering
Sensors and Transducers | Year: 2011

Presently, the need for power quality (PQ) monitoring instrument to characterize the performance of power system is becoming more important. Advancement in the embedded web based technology has enabled PQ data to be monitored and captured remotely via the web browser. This paper presents the development of a web-based PQ monitoring instrument for single phase power measurements. The embedded web based technology is applied and this contributes to the reduction in the development and operational cost of the PQ instrument. The PQ data is processed at the receiving end so as to eliminate dependency in processing the PQ data at customer sites. The results on real-time monitoring and downloading of the PQ data via the web browser are also described. The novelty of the developed PQ monitoring instrument is in the simplicity of the design and cost of developing the instrument. © 2011 IFSA. Source


Abdullah H.,Electronics and System Engineering | Salwani I.,Electronics and System Engineering | Saari S.,Photonic Technology Laboratory
Ceramic Engineering and Science Proceedings | Year: 2014

Thin films of Cu doped with ZnS were synthesized using sol-gel method to be applies as anti-reflective coating. This research involving three different Cu concentrations which being doped to the ZnS and then the thin film were heated at 550 °C for 1 hour. Anti-reflecting coating is prepared by doping Cu to ZnS with the equation Zn1-xCuxS where x = 0.00, 0.05, 0.10, 0.15 and 2.0. The effect of Cu2+ doping on structural, microstructural and the cell performance. The structural of ZnS:Cu thin films was characterized by X-ray diffractometer (XRD). The patterns show two consistent peaks of monoclinic structure at (2 0 0) and (1 2 2). Microstructure images of anti-reflecting layer have been observed using Scanning Electron Microscope (SEM). The images show the formation of flakes morphology. The Efficiency of the silicon solar cell has been measured using Electrochemical Impedance Spectroscopy (EIS). The efficiency of the silicon solar cell without anti-reflecting coating gave the value of 0.000008%, while efficiency of silicon solar cell with anti-reflecting coating gave the value of 0.00011%. It is clear that the result obtained has been proven, that anti-reflecting coating helps the enhancement of light absorption. Copyright © 2015 by The American Ceramic Society. Source


Abdullah H.,Electronics and System Engineering | Omar A.,Electronics and System Engineering | Asshaari I.,National University of Malaysia | Yarmo M.A.,National University of Malaysia | And 4 more authors.
Ceramic Engineering and Science Proceedings | Year: 2014

ZnO-CNTs thin films were prepared by chemical bath deposition (CBD) method. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and electrochemical impedance spectroscopy (EIS) were employed to analyze the influence of annealing temperature effects on the morphological, structural and photovoltaic properties of the ZnO-CNTs thin films. XRD measurement indicated that the crystallite size of ZnO-CNTs hexagonal wurtzite structure varies from 18 nm to 34 nm. FESEM image shows porous structures of ZnO-CNTs thin film annealed at 250, 300 and 350 °C. The CNTs like fibre appeared in the porous structure of the thin film annealed at 250 °C. Photovoltaic performances measured the power conversion efficiency, η, photocurrent density, Jsc, open-circuit voltage. Voc and fill factor, FF of the ZnO-CNTs photoanodes. The highest power conversion efficiency of 1.07 % was achieved for the photoanode annealed at 350 °C. The electron transport parameters such as electron lifetime, τeff, electron recombination lifetime, keff, effective electron diffusion coefficient, Deff, effective electron diffusion length, Ln, series resistance, Ri. charge transport resistance, Rcl and transport resistance, R1 of the ZnO-CNTs photoanode were analyzed accordingly. The annealing temperature of 350 °C can be proposed as a suitable heat treatment effect to obtain a good structural, morphological and photovoltaic properties although with a bad electron transport properties. Copyright © 2015 by The American Ceramic Society. Source

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