Rosnita Muhammad1, Zulkafli Othaman2,Samsudi Sakrani1
1Ibnu Sina Institute for Fundamental Science Studies,
Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia
2Physics Department, Faculty Of Science,
Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia
Epitaxy is an affordable method for growing high quality crystalline in quantum devices applications. The fabrication of the quantum devices is an outstanding challenge in nanostructure materials science. During last few years, a lot of attention has been devoted to the growth and characterization of quantum dots by using epitaxy method. In this paper, we present several epitaxy methods in recent advancement. We then briefly examine MOVPE systems starting with basic chemical reaction process, gas delivery equipment, reaction and safety. Growth mechanisms and criteria for growth rate are also described. Lastly, we examine and compare the MOVPE system at our place, Ibnu Sina Institute University Technology Malaysia.
Process Development and Optimization of Laser Diode To Single-Mode Fiber Coupling And Packaging Using Laser Welding Technique
Fadhali M A*, Zinal J, Munajat Y, and Rahman R
Optoelectronic laboratory, Physics Dept., Faculty of Science, UTM,
81310 Skudai, Johor, Malaysia
The rapid development in optical communications requires stable and high coupling efficiency optoelectronic devices in high yield, mass quantities at lower costs. Packaging process remains a bottleneck for the cost-effective manufacturing of the optoelectronic devices. The design parameters in the process development are numerous. In this work we used discrete lens coupling using two ball lenses in confocal configuration, result of the obtained coupling efficiency and misalignment tolerances both theoretically and experimentally are presented. The effect of laser welding beam parameters such as peck power density, focusing position on the target, pulse duration, and pulse repetition rate on the spot weld dimensions for two different alloys ( Kovar and stainless steel 304) as welding tools materials are presented which show that a peak power density of the range of (5*105 w/cm2 ) is suitable for laser welding in photonic devices packaging where the heat affected zone ( HAZ) has to be minimized to prevent the damage of sensitive optical components inside the module package. That value lead to an optimization of the laser weld depth and width ratio. A mathematical mode has been developed to estimate the penetration depth as a function of the incident power which shows the linear relation ship between power and penetration depth materials are s work is to study the respective contribution of each of the many parameters in the process development on coupling and packaging reliability.
Preliminary Analysis for Data Collection on Vehicle Inspection
Nuzulha Khilwani Ibrahim, Rozana Diana Ahmad Rusli, Nurulhuda Firdaus Mohd Azmi
Centre of Advanced and Software Engineering,
Universiti Teknologi Malaysia City Campus, Jalan Semarak, 45410 Kuala Lumpur
This paper presents a preliminary analysis of data collection on vehicle inspection centre. From the original data collected, data was improved by a little adjustment. The average value for every step of inspection is calculate to get a brief idea on how much time taken by every inspection for each vehicle before the value approximate into a range of additional maximum five seconds. There is a clash between two vehicles at some point in this analysis, which it define by two vehicles conflicting in two same time period at some point in first and second inspecting vehicle process. Knowing that there is a clash between the two series of same colored points, we tried to resolve the situation by adding a period of time called ‘waiting time’ to make sure that the conflicting points would be separated into different time units. In this research, we offer solutions using constraint programming techniques, with aims to improve the inspection process with greater efficiency and throughput.
Taylor Series Expansion Model for Optical Free Space Feedforward Linearization System
A. B. Maiteeg, S. M. Idrus, H. Harun
Photonic Technology Centre,
Faculty of Electrical Engineering,
Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia
One primary limitation on the performance of the optical transceiver is the nonlinearity of the laser transmitter, which produces intermodulation distortions and necessitates various compromises between modulation depth, channel spacing and types of modulation scheme, leading to degraded bandwidth efficiency. Nonlinearity of a directly modulated laser diode imposes limitations in the performance of the optical communication systems. Many laser linearization techniques involve the use of duplicate lasers or optical modulators, and those, which attempt to create physical structures within the optical modulators, and lasers can obviously increase the cost relative to ordinary optical transmitters. Fundamentally, linearization techniques can be divided into one of the following categories: feedforward, feedback, precorrective distortion. In this paper a new free space optical link non-linearity correction system has been introduced employing the Feedforward Linearization technique, so called Optical Free Space Feedforward Linearization System (OFFLS). The system was modeled by Taylor series and the results of the simulations have shown a significant reduction in the 3th and 5th order intermodulation distortion products (IMD) by 30 dB over 2GHz bandwidth.
Morphology and Optical Properties of Silicon Nanocrystals embedded in Silicon oxide
Yussof Bin Wahab, Yeong Wai Woon, Karim Bin Deraman
Physics Department, Faculty of Science,
Universiti Teknologi Malaysia, 81310 UTM, Skudai, Johor
Crystalline Silicon (Si) being dominant in electronic industry has an indirect bandgap, and therefore is incapable of light emission. The light emission from low dimensional Si, especially nano-scale Si, has attracted a strong interest since the Canham’s report1 on the strong visible photoluminescence from porous Si at room temperature. Among the many types of Si nanostructures, Si nanocrystals (Si-NCs) embedded in amorphous silica matrix has been extensively studied due to their unique optical properties, simplicity of producing, and the technological compatibility with present Si integrated circuits. Here, we report our investigation on the structural and optical properties of Si-rich Si oxide (SiOx) films with different values of x (x<2), which were deposited by magnetron RF co-sputtering technique. The SiOx film composition has been controlled by varying the number of Si chips being placed on the pure SiO2 target during the sputtering process. These films were rapid thermal annealed in nitrogen gas at high temperature to form Si-NCs embedded in SiO2. The focus of our study is on the effect of excess Si concentration on the properties of Si-NCs. Light emission from the Si-NCs is investigated by using photoluminescence (PL). Spectroscopic ellipsometry, UV-Vis-NIR spectrometer was used to obtain accurate information about film thickness and refractive index of material. Structural characterization method, such as atomic force microscope (AFM), field emission scanning electron microscopy (FESEM) and Infra-red spectroscopy, were also used to obtain general surface characteristics and nanostructure patterns in order to assist in the understanding of the underlying PL mechanism of the Si-NCs.
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