Now showing 1 - 10 of 19
  • Publication
    Remazol orange dye sensitized solar cell
    Water based Remazol Orange was utilized as the dye sensitizer for dye sensitized solar cell. The annealing temperature of TiO2 working electrode was set at 450 °C. The performance of the device was investigated between dye concentrations of 0.25 mM and 2.5 mM at three different immersion times (3, 12 and 24 hours). The adsorption peak of the dye sensitizer was evaluated using UV-Vis-Nir and the device performance was tested using solar cell simulator. The results show that the performance was increased at higher dye concentration and longer immersion time. The best device performance was obtained at 0.2% for dye concentration of 2.5 mM immersed at 24 hours.
  • Publication
    Characterization of all-optical Tofolli and Peres gates employing optimized SOA-NOLM
    In this work, all-optical reversible gates namely Tofolli and Peres are studied and characterized. The gates utilize semiconductor optical amplifier (SOA) in nonlinear loop optical mirror (NOLM). The reversible gates are performed at data rate 10 Gb/s with narrow Gaussian pulses as input signals. Delay of 130 ps and injection current of 170 mA have displayed the optimum outputs in the SOA-NOLM. Extinction ratio is greatly reduced, thus less noise interferes the logic operation in this simple technique. It is observed that Peres gate has shown a higher output power compare to Toffoli gate. This could be due to multiple amplification that are experienced by the signals. Other than the gain, injection current and delay are shown to give major effect in producing the correct bits at the outputs. The SOA-NOLM also can be cascaded for other arithmetic signal processing operation at high frequency. It is also recorded that the design consumes low power especially in small signal gain process. Thus, the design indicates its versatility to be executed in photonic integrated circuits for ultrafast signal control through fiber networks.
  • Publication
    UWB triplet and quadruplet pulses generation employs nonlinear effect in semiconductor optical amplifier nonlinear loop mirror
    ( 2020-01-08)
    Zahari, Suhaila Mohd
    ;
    ; ; ;
    Ghazali N.F.
    ;
    Shahimin M.M.
    Ultrawideband (UWB) triplet and quadruplet pulses generation exploits nonlinear effect in semiconductor optical amplifier (SOA) in nonlinear loop mirror (NOLM) is investigated in this work. Two signals are transmitted through the SOA-NOLM simultaneously to create cross-phase modulation (XPM) effect. Firstly, the XPM causes the production of doublet which later combines for creation of triplet and quadruplet. This technique engages a proper tuning of optical delay and a selection of suitable power in all loops. Besides, injection current of the SOAs also governs the formation of these pulses. Although, frequency of the signals can be varied accordingly, the pulses are limited to certain adjustment that shifted its position in time domain. Furthermore, the set up can also be assessed for monocycle and doublet pulses by extracting the output at several positions. It can be concluded that the design may work as multiple pulses generation. All pulses are examined and compared with their electrical spectrum counterpart for validity of this approach.
  • Publication
    Critical analysis of stability and performance of organometal halide perovskite solar cells via various fabrication method (Review)
    ( 2017)
    Suriati Suhaimi
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    ; ; ;
    Vithyacharan Retnasamy
    ;
    Mukhzeer Mohamad Shahimin
    Organometal halide perovskite solar cells (Omh-PSCs) have attracted attention due to its unique electrical and optical properties. Ideally, the Omh-PSCs should remain free from degradation under normal operating conditions for several years, preferably tens of years. In order to produce high power conversion efficiency with low potential of degradation, different fabrication methods have been developed. The reported stability of perovskite films can vary significantly and reported to decay substantially up to 20% of its original performance. A thorough understanding of fabrication process upon the stability of the device is regarded as crucial to pave the way for future endeavors. This review summarized and highlighted the recent research of fabrication methods that gave an impact to the stability of perovskite devices.
  • Publication
    Geometrical optimization of lithium niobate on insulator rib waveguide for quantum communication application
    Recently, thin film Lithium niobate has been recognized as an alternative material to silicon based technology due to its capability to support a broader range for quantum communication system. With the aim to operate within single photon application, we demonstrate the mode distribution, propagation constant and effective refractive indices of the Lithium Niobate on Insulator rib waveguide which operates at both fundamental wavelength, 1550 nm and second harmonic wavelength, 775 nm, respectively by using Finite Element Method. The etched depth and width of the core was varied from 340 to 400 nm and 700 to 1400 nm, respectively with the thickness of slab is fixed at 100 nm. From the result, it shows the effective refractive index increases gradually with the increment of etched depth and width of core, respectively. At second harmonic wavelength, the effective refractive indices and propagation constant shows a significant increment compare to observation at 1550 nm with an ability to produce both fundamental mode and first order mode across the structure.
  • Publication
    Thermal analysis of LED packaging with single-walled carbon nanotube heat sink
    The thermal issue is still the bottleneck of a light emitting diode (LED) system to sustain its operational performance. In this paper, we design, simulated, and analysed an LED packaging with single walled carbon nanotubes as a heat sink. The 5W LED packaging is simulated with different types of LED chips materials which comprise gallium nitride, indium nitride, zinc oxide, zinc selenide and titanium dioxide. Using LED chips materials as the heat source, the heat flow is conducted through the bottom layer to the heat sink and dissipates by convection or radiation heat transfer to the surrounding. The addition of thin film on top of the phosphorus layer functions to enhance the recombination rate and guided the flow of heat to the bottom. The 5W titanium dioxide light emitted diode packaging (LED packaging C) has been successfully demonstrated to have overall temperature reduced to around ~10°C by using single walled carbon nanotube heat sink as compared to copper heat sink and aluminium heat sink. Meanwhile, carbon material as thermal interface material and substrate also plays a major role as a thermal cooling solution in LED packaging. For 5W titanium dioxide light emitted diode packaging, under self-heating conditions, the maximum average temperature generated is 81.05 °C. Despite that, under convection conditions, the maximum average temperature generated is 41.53°C.
      6  25
  • Publication
    The production of Malaysia bamboo charcoal (Gigantochloa albociliata) as the potential absorbent
    Bamboo charcoal was successfully carbonized at 500 °C and 800 °C using Malaysia buluh madu (Gigantochloa albociliata). Structural analysis was done using Atomic Force Microscopy (AFM) in two different solvents; ethanol and DI water. The functional groups of bamboo charcoal were confirmed using Fourier Transform Infrared Spectroscopy (FTIR). The adsorption property of bamboo charcoal solution was investigated at different concentrations of 0.2, 0.4 and 0.7 mg/mL, using methylene blue test and characterized using UV-Vis Spectroscopy. Based on the adsorption investigation, it shows that the adsorption was increased as the concentration increased. It was also shown that at higher temperature and longer duration time, the adsorption process is improved.
      28  1
  • Publication
    Optimization of wireless power transfer using artificial neural network: A review
    Wireless power transfer (WPT) is widely explored and applied nowadays because of its simplicity in transferring power without using wire, easy maintenance, and equipment mobility. Due to mobility and compatibility attributes, WPT is utilized in powering biomedical devices, small electronic equipment, wireless sensor, mobile phones, and high voltage applications (eg, electric vehicles). The implementation of artificial neural network (ANN) in WPT has emerged as a powerful/prominent tool for estimating the performance parameters due to its learning and significant features. Such implementation can minimize design complexity and time-consuming calculations. An early application of ANN employs the information derived from the collectively measured processes for training the ANN algorithm. After a suitable training process, the network output can be considered in place of computationally thorough representations to speed up the result search. To obtain precise result and optimize the parameters in WPT, several popular ANN algorithms have been used by researchers. This review paper highlighted the latest research specifically regarding the implementation of ANN in WPT, which included the types of ANN implemented in WPT, current WPT problem investigation that used ANN, and a comparison between the techniques. Moreover, the challenges and constraints of ANN techniques were elucidated at the end of this paper.
      2  23
  • Publication
    Characteristics of multiwavelength fiber laser employing semiconductor optical amplifier in nonlinear optical loop mirror with different length polarization maintaining fiber
    In this paper, we propose and demonstrate generated characteristics of a multiwavelength fiber laser based on semiconductor optical amplifier in a nonlinear optical loop mirror with different length of polarization maintaining fiber. The configuration comprises 3-dB optical coupler, semiconductor optical amplifier and, 2 meters and 10 meters of polarization maintaining fiber. Characteristics of multiwavelength fiber laser are studied through the use of polarization maintaining fiber at different lengths. The experimental results revealed the number of lasing lines increases with the increment of the polarization maintaining fiber length. The polarization maintaining fiber with 10 meters of length has the ability to generate a higher number of lasing lines up to 47 signals with semiconductor optical amplifier injected current at 180mA, respectively. However, in terms of average peak power and average optical signal to noise ratio, the 2 meter of polarization maintaining fiber length has the capability to produce a higher value which is 0.45mW at 250mA of semiconductor optical amplifier driven current and 28.86dB at 170mA of semiconductor optical amplifier driven current, respectively. Furthermore, it is observable that this configuration capable to generate a wider bandwidth which is operating in the conventional (C) band to long (L) band at the room temperature.
      33  1
  • Publication
    Digital fringe projection for hand surface coordinate variation analysis caused by osteoarthritis
    ( 2017) ;
    Cheek Hau Tan
    ;
    Vithyacharan Retnasamy
    ;
    Rajendaran Vairavan
    ;
    Muhammad Hafiz Ab Aziz
    ;
    ; ; ;
    Hand osteoarthritis is one of the most common forms of arthritis which impact millions of people worldwide. The disabling problem occurs when the protective cartilage on the boundaries of bones wear off over time. Currently, in order to identify hand osteoarthritis, special instruments namely X-ray scanning and MRI are used for the detection but it also has its limitations such as radiation exposure and can be quite costly. In this work, an optical metrology system based on digital fringe projection which comprises of an LCD projector, CCD camera and a personal computer has been developed to anticipate abnormal growth or deformation on the joints of the hand which are common symptoms of osteoarthritis. The main concept of this optical metrology system is to apply structured light as imaging source for surface change detection. The imaging source utilizes fringe patterns generated by C++ programming and is shifted by 3 phase shifts based on the 3 steps 2 shifts method. Phase wrapping technique and analysis were applied in order to detect the deformation of live subjects. The result has demonstrated a successful method of hand deformation detection based on the pixel tracking differences of a normal and deformed state.
      5  22