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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.

Matin M.A.,Electronics and System Engineering | Amin N.,Electronics and System Engineering | Amin N.,Solar Energy Research Institute | Zaharim A.,Solar Energy Research Institute | Sopian K.,National University of Malaysia
WSEAS Transactions on Environment and Development | Year: 2010

Polycrystalline cadmium telluride (CdTe) is the leading material for realization of low cost and high efficiency solar cell for terrestrial use. In this work, a conventional structure of CdTe thin film solar cells [1] was investigated and conversion efficiency as high as 13.2% was achieved with the CdTe baseline structure of SnO2/CdS/CdTe. To explore the possibility of ultra thin and high efficiency CdS/CdTe solar cells, the CdTe absorber layer and CdS window layer were decreased to the extreme limit and 1 μm thin CdTe layer is found to show reasonable range of efficiency with stability. Moreover, it was found that there were scopes to increase cell efficiency by reducing the cadmium sulfide (CdS) window layer thickness. The CdS window layer was reduced to 60 nm together with the insertion of zinc oxide (ZnO) or zinc stannate (Zn2SnO4) as the buffer layer to prevent forward leakage current. All the simulations have been done using Analysis of Microelectronic and Photonic Structures (AMPS 1D) simulator. The maximum conversion efficiency of 18.3% (Voc = 1.00 V, Jsc = 26.15 mA/cm2, FF = 0.769) was achieved with 1 μm-CdTe absorber layer, 60 nm-CdS window layer and 100 nm of ZnO or Zn2SnO4 buffer layer. Furthermore, it was found that the cell normalized efficiency linearly decreased with the increasing operating temperature at the gradient of -0.4%/°C, which indicated better stability of the CdS/CdTe solar cells.

Menon P.S.,National University of Malaysia | Kumarajah K.,Electronics and System Engineering | Bais B.,Electronics and System Engineering | Abdullah H.,Electronics and System Engineering | And 2 more authors.
IEEE International Conference on Semiconductor Electronics, Proceedings, ICSE | Year: 2010

Long-wavelength vertical-cavity surface-emitting lasers (LW-VCSELs) have profound advantages over the traditional edge-emitting lasers offering improved properties with respect to mode selectivity, fiber coupling, threshold currents and integration into 2D arrays or with other electronic devices. Its commercialization is gaining momentum as the local and access network in optical communication system expands. This paper reports the optimization of the peak lasing power and peak lasing wavelength of a LW-VCSEL using a numerical-based simulator and Taguchi's orthogonal array methodology. Initially, peak lasing power increment of 96.5% was achieved at 9.51 mW with peak wavelength of 1.55956 μm. Next, we attempted to bring the peak wavelength on target to 1.55 μm. It was found that a reduction of DBR mirror thicknesses by 1.3% from its nominal values is able to produce a device with lasing powers of 11.62 mW and on-target peak wavelength of 1.55 μm. © 2010 IEEE.

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.

Idros M.F.M.,University Technology of MARA | Hashim H.,University Technology of MARA | Islam S.,National University of Malaysia | Ali S.H.,Electronics and System Engineering
Sensors and Transducers | Year: 2012

This paper presents the optical capability in monitoring the variation of light transmittance in the lubricant oil due to the oxidation by using Embedded MATLAB Function (EMF) tools. Recently, the increasing amount of used engine oil has been due to the car's manufacturer that recommended users to change their engine oil at a constant time or according to mileage interval. This will make a possibility of substantial increases of used engine oil because it changed more frequently than necessary. Therefore, a condition based technique is introduced to monitor the oxidation of lubricating engine oil by using EMF. By applying the regression analysis in EMF, the result shows that the slopes varied according to the degradation trends. Therefore, the capability of optical with combination of embedded tools to predict the degradation lifetime has been proven as compared to the others work that only analyzed the degraded condition without predict the future condition. © 2012 IFSA.

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.

Abdul kadir A.F.,Electronics and System Engineering | Mohamed A.,Electronics and System Engineering | Shareef H.,Electronics and System Engineering | Che Wanik M.Z.,Electronics and System Engineering
Turkish Journal of Electrical Engineering and Computer Sciences | Year: 2013

Growing concerns over environmental impacts, improvement of the overall network conditions, and rebate programs offered by governments have led to an increase in the number of distributed generation (DG) units in commercial and domestic electric power production. However, a large number of DG units in a distribution system may sometimes contribute to high levels of harmonic distortion, even though the emission levels of the individual DG units comply with the harmonic standards. It is known that the nonoptimal size and nonoptimal placement of DG units may lead to high power losses, bad voltage profiles, and harmonic propagations. Therefore, this paper introduces a sensitivity analysis to determine the optimal location of DG units, as well as evolutionary programming and harmonic distribution load ow for determining the optimal size of DG units in radial distribution systems. A multiobjective function is created to minimize the total losses and average total harmonic distortion voltage (THDv) of the distribution system. The proposed methodology is tested with a 69-bus radial distribution system. The proposed optimal placement and sizing of the DG units is found to be robust and provides higher efficiency for the improvement of the voltage profile and the minimization of the losses and THDv.

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.

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.

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