Hairul Azhar Abdul Rashid
Multimedia University
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Publication
Featured researches published by Hairul Azhar Abdul Rashid.
Optics Express | 2009
M. N. Mohd Nasir; Z. Yusoff; M. H. Al-Mansoori; Hairul Azhar Abdul Rashid; P. K. Choudhury
A widely tunable low stimulated Brillouin scattering (SBS) photonic crystal fiber (PCF) based multi-wavelength Brillouin-erbium fiber laser is presented. The fiber laser structure utilizes a pre-amplified Brillouin pump (BP) technique with 100 m of PCF and a tunable band-pass filter within a Fabry-Perot cavity. A total of 14 Brillouin Stokes lines can be tuned over 29 nm from 1540 nm to 1569 nm. The wide tunability was only limited by the bandwidth of the tunable band-pass filter. A constant channel spacing of 0.079 nm and signal to noise ratio (SNR) of more than 20 dB for each Brillouin Stokes lines were also observed.
Journal of The Optical Society of America B-optical Physics | 2009
Mohammad I. Johari; Azin Adamiat; Nurul Shahrizan Shahabuddin; M. N. Mohd Nasir; Z. Yusoff; Hairul Azhar Abdul Rashid; Mohammed Hayder Al-Mansoori; P. K. Choudhury
Utilization of a partially reflective fiber Bragg grating in the development of a multiwavelength Brillouin-erbium fiber laser is proposed. A ring cavity with a preamplified Brillouin pump configuration is implemented to demonstrate much better performance in comparison with the previously reported results obtained with different configurations. The combination of a 7 km long single-mode fiber and a 10 m long erbium-doped fiber ultimately yields the generation of up to twenty-one Brillouin Stokes lines. The laser configuration provides a greater tuning range of 21 nm at a Brillouin pump power of 2 mW and 980 nm pump power of 20 mW, and requires a much lower pump power to initiate lasing.
Journal of Lightwave Technology | 2012
S. D. Emami; Hairul Azhar Abdul Rashid; S. Z. M. Yasin; K. A. M. Shariff; M. I. Zulkifli; Z. Yusoff; H. Ahmad; S. W. Harun
A new method for gain enhancement in a S-band thulium-doped fiber amplifier (TDFA) co-doped with aluminum is demonstrated using a macro-bending approach. The macrobending of the doped fiber in a small radius suppresses both amplified spontaneous emissions (ASEs) at 800 and 1800 nm band and thus increases the population inversion in the S-band region. The numerical aperture and core radius of the doped fiber are optimized so that 800 nm ASE propagates with higher order modes to achieve a significant suppression while the loss is minimum in the S-band region. Meanwhile, the 1050 nm pump wavelength should propagate in the fundamental mode to maximize the overlap factor and thulium ion absorption so that the ASE loss is maximum at the 1800 nm region. Gain enhancements of about 5-8 dB are obtained with macrobending at the wavelength region between 1420 and 1470 nm.
ieee international conference on semiconductor electronics | 2006
Syamsuri Yaakob; Mohd Azmi Ismail; Romli Mohamad; Mohamed Razman Yahya; Abd. Fatah Awang Mat; M. R. Mokhtar; Hairul Azhar Abdul Rashid
This paper presents the evaluation of radio over fibre (ROF) capability with electroabsorption modulator (EAM) as a downlink photodetector (PD) and uplink radio frequency (RF) modulator. The results show that the EAM device has potential to be adopted as the transceiver at the remote antenna unit (RAU) for the system. The 130 m ROF system with biased EAM is capable to obtain a symmetrical WLAN 802.11a data rate of 18 Mbps with laser diode output power of 8.7 dBm.
2008 6th National Conference on Telecommunication Technologies and 2008 2nd Malaysia Conference on Photonics | 2008
S.A. Daud; S. D. Emami; Hairul Azhar Abdul Rashid; M. R. Mokhtar; Z. Yusoff; Faidz Abd Rahman
This paper presents an experimental study of the performance characteristics of an S-band single pass and double pass erbium-doped fiber amplifier (EDFA), using depressed cladding erbium-doped fiber (EDF). The depressed cladding EDF is essentially used to suppress the amplified spontaneous emission (ASE) at the longer wavelength to achieve high amplification in the S-band region. Both single pass and double pass 980 nm pumping are considered. Gain and noise figure of the EDFA are measured. Double pass EDFA shows a significant gain increase of 14 dB in comparison to single pass configuration.
2008 6th National Conference on Telecommunication Technologies and 2008 2nd Malaysia Conference on Photonics | 2008
M. N. Mohd Nasir; Zubaida Yusoff; M. H. Al-Mansoori; Hairul Azhar Abdul Rashid; P. K. Choudhury
In this paper, we demonstrate an efficient multi-wavelength Brillouin-erbium fiber laser with a pre-amplified Brillouin pump within a Fabry-Perot cavity. With the utilization of a fiber Bragg grating filter as one of the fiber loop mirrors, up to 25 stable Brillouin Stokes lines could be generated with channels spacing of 0.088 nm. The architecture of the design needs only 3 dBm of the Brillouin pump power and 90 mW of the 980 nm laser diode to produce the 25 maximum output channels.
asia optical fiber communication and optoelectronics conference | 2007
M. N. Mohd Nasir; M. H. Al-Mansoori; Hairul Azhar Abdul Rashid; P. K. Choudhury; Z. Yusoff
We demonstrate an efficient multi-wavelength Brillouin-erbium fibre laser incorporating an FBG filter. The self-lasing effect is reduced and subsequently the number of output channels increased. Furthermore, the stability of output channels is also improved.
IEICE Electronics Express | 2007
Nadir Hossain; A. W. Naji; Vivekanand Mishra; Abbou F. Mohammed; Hairul Azhar Abdul Rashid; Faidz Abd Rahman
A simple rate equation model of double pass (DP) Erbium doped fiber amplifier (EDFA) is developed based on the Giles and Desurvire (1991) model of single pass (SP) EDFA. The mathematical equations to calculate stimulated absorption and emission rate between level 1 and 2 of SP EDFA are modified by integrating the reflected backward propagating signal of DP EDFA. Reflection loss of signal by the reflector is included with the backward propagating signal of DP EDFA. A combination of Runge-Kutta and relaxation method is used to numerically solve the developed DP EDFA rate equation model. Considering high gain and low noise figure (NF) by very low remote pump power as main design objective, the design procedure of remotely pumped optimized DP EDFA is described. Finally the robustness and stability of the developed DP EDFA rate equation model are shown by analyzing the numerical results and output shape using various design parameters.
Computers & Electrical Engineering | 2007
Ganesan Periakarruppan; Hairul Azhar Abdul Rashid
In todays modern telephony network, VoIP is fast emerging as one of the main communication techniques. However, the performance and the quality of VoIP are affected by echo. Packet Based Echo Canceller (PBEC) is introduced, as a solution to cancel echo in the VoIP network. PBEC can replace the current echo cancellers, which are located in the Public Switched Telephony Network (PSTN) central switches. The operating principle of the PBEC is explained and its advantages are highlighted. The performance of the PBEC using different speech codecs is also studied. Using the PBEC, a maximum Echo Return Loss Enhancement (ERLE) of 37.39dB has been achieved when used with the Pulse Code Modulation (PCM) based speech codec. From the simulation results, it can be seen that the performance of the Adaptive Differential Pulse Code Modulation (ADPCM) clearly matches the performance of the PCM based speech codec. The other major problem affecting the VoIP network is the issue of packet loss. This issue of packet loss has been successfully addressed in this paper by the insertion of random values. With the insertion of random values, the ERLE increases by 4.81dB compared to when there is no insertion of random value. The PBEC with the utilization of random values would make the VoIP a better communication tool.
Archive | 2016
S. D. Emami; Richard Penny; Hairul Azhar Abdul Rashid; Waleed S. Mohammed; B. M. Azizur Rahman
This chapter describes an analytical model developed to study the Fano resonance effect in clusters of spherical plasmonic nanoparticles under local excitation. The model depicted the case of a parallel single dipole emitter that was near-field coupled to a pentamer or heptamer cluster of nanospheres. Spatial polarization and field distributions of the optical states and resonance spectra for these cluster configurations were calculated. The directivity calculation was analyzed in order to qualify the redirection of emission. Performances of various nanoantennae were investigated and fully characterized in terms of spatial geometric differences and the Fano resonance effect on plasmonic nanoparticles in the optical domain. Light radiation patterns were found to be significantly affected by nanosphere sizes and positioning of nanospheres with respect to the dipole. A coupling capacitor is calculated as an equivalent component in the proposed circuit model in order to describe the coupling effect between subradiant and superradiant mode in the Fano resonance. The circuit impedances of tetramer, pentamer, and broken symmetry pentamer are simulated, with resultant circuit models in agreement with the calculated results based on S-parameters. The analytical treatment of these modeled nanoantennae yielded results that are applicable to physical design and utilization considerations for clusters in nanoantennae mechanisms.