Mohamad Halim Abd. Wahid
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Preferred name
Mohamad Halim Abd. Wahid
Official Name
Mohamad Halim, Abd. Wahid
Alternative Name
Wahid, M. H.A.
Wahid, Mohamad Halim Abdul
Main Affiliation
Scopus Author ID
5478542340
Researcher ID
DTC-0242-2022

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  • Publication
    UWB triplet and quadruplet pulses generation employs nonlinear effect in semiconductor optical amplifier nonlinear loop mirror
    ( 2020-01-08)
    Zahari, Suhaila Mohd
    ;
    Mohamad Halim Abd. Wahid
    ;
    Nor Azura Malini Ahmad Hambali
    ;
    Nurjuliana Juhari
    ;
    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
    Characterization of all-optical Tofolli and Peres gates employing optimized SOA-NOLM
    ( 2020-01-08)
    Nur Hafizah Ghazali
    ;
    Mohamad Halim Abd. Wahid
    ;
    Nor Azura Malini Ahmad Hambali
    ;
    Nurjuliana Juhari
    ;
    Zahari S.M.
    ;
    Shahimin M.M.
    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.
      1  39
  • Publication
    Multiwavelength fiber laser employing semiconductor optical amplifier in nonlinear optical loop mirror with polarization controller and polarization maintaining fiber
    ( 2020-01-08)
    Husshini N.F.H.
    ;
    Nor Azura Malini Ahmad Hambali
    ;
    Mohamad Halim Abd. Wahid
    ;
    Shahimin M.M.
    ;
    Mohd Najib Mohd Yasin
    ;
    Norshamsuri Ali @ Hasim
    ;
    Al-Asadi H.A.A.
    ;
    Raghavendra C.G.
    This paper demonstrates multiwavelength fiber laser employing semiconductor optical amplifier in nonlinear optical loop mirror with polarization controller and polarization maintaining fiber. The configuration consists of a 3-dB coupler, polarization controller and several lengths of polarization maintaining fiber. The results showed a single polarization controller with 5 meters of polarization maintaining fiber length generated 36 of lasing lines at 160mA of semiconductor optical amplifier current. In addition, for the average peak power and average optical signal to noise ratio, the 2 meters of polarization maintaining fiber length with single polarization controller in the nonlinear optical loop mirror shows higher values, 0.55mW at 210mA and 31.98dB at 210mA, respectively. Both gain media have a wider bandwidth operating in the C-band and L-band at room temperature.
      27  1
  • Publication
    Characteristics of multiwavelength fiber laser employing semiconductor optical amplifier in nonlinear optical loop mirror with different length polarization maintaining fiber
    ( 2020-01-08)
    Husshini N.F.H.
    ;
    Nor Azura Malini Ahmad Hambali
    ;
    Mohamad Halim Abd. Wahid
    ;
    Shahimin M.
    ;
    Mohd Najib Mohd Yasin
    ;
    Norshamsuri Ali @ Hasim
    ;
    Al-Asadi H.A.A.
    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.
      37  1
  • Publication
    Design of arrayed waveguide grating (AWG) demultiplexer based PMMA for narrow channel spacing
    ( 2020-01-08)
    Nurjuliana Juhari
    ;
    Yusof, Muhammad Fadzliazuan
    ;
    Mohamad Halim Abd. Wahid
    ;
    Nur Syakimah Ismail
    Arrayed Waveguide Grating (AWG) based PMMA polymer that functioning as multiplexer/demultiplexer (mux/de-mux) having good potential in WDM system and interferometer optical sensor. Besides, AWG is suitable for larger count optical signals and good filter response devices. AWG demultiplexer based polymer was simulated using Beam Propagation Method (BPM) under TE mode with 1550 nm central wavelength. This work explores the performance of polymer-based AWG with straight waveguide structure that capable to produce 16-channels AWG device for 100 GHz (0.8 nm) channel spacing. The 16-channels AWG based polymer produces low insertion loss of 3.430 dB and low crosstalk of -24.763 dB. The central wavelength for each output port gives almost similar values with the standard ITU-T DWDM wavelength grid with the smallest difference of 0.5 nm. This proposed device also capable to solve the demand on higher channel capacity especially to support internet usage and the needs of the best communication system.
      37  3