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ABSTRACT: We implement a particle swarm optimization (PSO) algorithm to characterize stimulated Brillouin scattering phenomena in optical fibers. The explicit and strong dependence of the threshold exponential gain on the numerical aperture, the pump laser wavelength and the optical loss coefficient are presented. The proposed PSO model is also evaluated with the localized, nonfluctuating source model and the distributed (non-localized) fluctuating source model. Using our model, for fiber lengths from 1 km to 29 km, the calculated threshold exponential gain of stimulated Brillouin scattering is gradually decreased from 17.4 to 14.6 respectively. The theoretical results of Brillouin threshold power predicted by the proposed PSO model show a good agreement with the experimental results for different fiber lengths from 1 km to 12 km.
Optics Express 01/2011; 19(3):1842-53. · 3.59 Impact Factor
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ABSTRACT: We develop a theoretical model that can be used to predict stimulated Brillouin scattering (SBS) threshold in optical fibers that arises through the effect of Brillouin pump recycling technique. Obtained simulation results from our model are in close agreement with our experimental results. The developed model utilizes single mode optical fiber of different lengths as the Brillouin gain media. For 5-km long single mode fiber, the calculated threshold power for SBS is about 16 mW for conventional technique. This value is reduced to about 8 mW when the residual Brillouin pump is recycled at the end of the fiber. The decrement of SBS threshold is due to longer interaction lengths between Brillouin pump and Stokes wave.
Optics Express 10/2010; 18(21):22339-47. · 3.59 Impact Factor
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ABSTRACT: We experimentally demonstrate a ring-cavity,
single-wavelength Brillouin-Raman fiber laser. An 11-km long
dispersion compensating fiber was used as the medium for
the Raman as well as the Brillouin amplification. A threshold
power of 27 mW was recorded to get the Brillouin-Stokes
line at 1455 nm pump wavelength. At an injected Brillouin
pump power of 2 mW, while the Raman pump unit was fixed at
a power of 296 mW, the single-wavelength Brillouin-Raman
fiber laser can be tuned from 1520 nm to 1580 nm without
any self-lasing cavity modes in the laser system. The Brillouin-
Stokes line has a 3-dB power fluctuation within 26 nm from
1542 nm to 1568 nm.
Laser Physics. Letters. 01/2010; 7:454–457.
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ABSTRACT: We present a single�wavelength Brillouin fiber laser utilizing a ring�cavity configuration. Performances and characteristics of the laser system have been investigated at different output coupling ratios. The optimum output power of the system stood at 7.3 mW, which was obtained at 90% output coupling ratio. A
low Brillouin threshold power of 0.9 mW was obtained at 10% output coupling ratio when the Brillouin pump was set at its maximum power of 24 mW.
Laser Physics 01/2010; 20(7):1618 – 1624. · 3.61 Impact Factor
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M. A. M. Azau,
A. F. Abas, M. I. Saripan,
W. A. Wan Adnan,
N. K. Noordin,
Ismail A,
Mokhtar M,
Samsudin K,
Mashohor S,
M.F.A. Rasid,
R. S. A. Raja Abdullah,
Arif F
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ABSTRACT: This paper presents a new method in engineering education called a continuous-grouped-self-learning (CGSL) system. In general, based on feedbacks acquired from the student at the end of the implementation, students better understanding and appreciation to the courses been taught. Out of 60 students 71.7% admitted that this learning system has improved their study style and knowledge acquisition, which then agreed to be implemented in future. The observation shows that this system increases the appreciation to the knowledge better than conventional method. Apart from that the system also produced better students in term of responsibility, self-confidence, competitiveness, group work, and knowledge sharing. This is realized with the implementation of mock teaching assessment.
International Education Studies. 01/2009;
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ABSTRACT: This paper describes the characteristics of the multihole collimator gamma camera that is simulated using the combination of the Monte Carlo N-Particles Code (MCNP) version 5 and in-house software. The model is constructed based on the GCA-7100A Toshiba Gamma Camera at the Royal Surrey County Hospital, Guildford, Surrey, UK. The characteristics are analyzed based on the spatial resolution of the images detected by the Sodium Iodide (NaI) detector. The result is recorded in a list-mode file referred to as a PTRAC file within MCNP5. All pertinent nuclear reaction mechanisms, such as Compton and Rayleigh scattering and photoelectric absorption are undertaken by MCNP5 for all materials encountered by each photon. The experiments were conducted on Tl-201, Co-57, Tc-99 m and Cr-51 radio nuclides. The comparison of full width half maximum value of each datasets obtained from experimental work, simulation and literature are also reported in this paper. The relationship of the simulated data is in agreement with the experimental results and data obtained in the literature. A careful inspection at each of the data points of the spatial resolution of Tc-99 m shows a slight discrepancy between these sets. However, the difference is very insignificant, i.e. less than 3 mm only, which corresponds to a size of less than 1 pixel only (of the segmented detector)00.
AIP Conference Proceedings 05/2008; 1017(1).
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ABSTRACT: The paper is dedicated to the continuation and improvement of the vehicle classification method of SISAR micro-sensors for ground vehicles previously presented in RADAR2004 and RADAR2005 [1–2]. In spite of a number of theoretical research efforts in the application of SISAR for target classification [1–4] , there are only few research concentrate on the classification processing to confirm the feasibility of SISAR's practicality. This paper begins with an overview and summary of the authors' previous research. Then a new research topic in the improvement of the classification performance for various scenarios using Neural Network is proposed. Finally experimental results, conclusions and recommendations are presented.
Radar Systems, 2007 IET International Conference on; 11/2007
