Now showing 1 - 6 of 6
  • 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.
  • Publication
    Nitrate (NO3-) prediction in soil analysis using near-infrared (NIR) spectroscopy
    ( 2020-01-08)
    Sabri, Mohd Shafiq Amirul
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    Laili M.H.
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    Laili A.R.
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    Ismail M.N.M.
    Nutrient composition in soil analysis is investigated by using nitrogen (N) in form of nitrate (NO3-) as a representative factor correlated with NIR spectroscopy spectral absorbance. NIR spectroscopy method of sampling has been tested to overcome time consuming, complex chemical analysis procedure and invasive sampling method in order to identify nitrate content in soil samples. Spectral absorbance data from range 950 nm to 1650 nm correlated with nitrate reading then tested through few pre-processing techniques. Five techniques have been listed as top performer, which are Multiplicative Scatter Correction using Common Offset (MSCCO), Multiplicative Scatter Correction (MSC), Range Normalization (RN), Mean Normalization (MN) and Reduced (R) technique. Data calibration and prediction of both data is evaluated using Partial Least Square Regression (PLSR) model. In the final analysis, R technique has achieved as top performer pre-processing technique for both calibration and prediction results, with the coefficient of determination (R2) values of 0.9991 and root mean square error (RMSE) values of 0.0886 for prediction. Overall, the correlation of NIRS absorbance data and nitrate can be obtained using PLSR model with R pre-processing technique. Henceforth, we can conclude that the NIRS method of sampling can be used to identify nitrate content in soil analysis by using time saving, non-invasive and less laborious method of sampling.
  • Publication
    Performance Analysis of Coherent Source SAC OCDMA in Free Space Optical Communication Systems
    In this paper, we investigate the performance of spectral amplitude coding optical code division multiple access (SAC OCDMA) systems under the effect of beat noise and turbulence. Three different multi-laser source configurations are considered in this analysis: shared multi-laser, separate multi-laser, and carefully controlled center frequency separate multi-laser. We demonstrate through Monte Carlo simulation that the gamma–gamma probability density function (pdf) cannot adequately approximate the measured intensity of overlapping lasers and that an empirical pdf is required. Results also show it is possible to achieve error-free transmission at a symmetrical data rate of 10 Gbps for all active users when only beat noise is taken into account by precisely controlling the center frequencies. However, only 30% of the active users can be supported when both beat noise and turbulence are considered.
  • Publication
    Prediction of soil macronutrient (nitrate and phosphorus) using near-infrared (NIR) spectroscopy and machine learning
    ( 2020-01-08)
    Laili A.R.
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    Laili M.H.
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    Amirul M.S.
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    ; ;
    Ismail M.N.M.
    Determination of basic soil macronutrients such as nitrogen (N), phosphorus (P) and potassium (K) that dissolve from organic matter (OM) prior to the plantation of fruit and vegetable corps is one of the important process of soil preparation towards precision farming. In this paper comparative analysis is performed for detection algorithm on OM, (N) and (P) sample using near infrared spectroscopy (NIRS) spectrometer in reflective mode with an effective range of 900nm to 1700nm. In pre-processing we execute data dimension reduction by combining multiple feature selection such as data normalization, permutation feature importance, principle component analysis, fisher linear discriminant and filter-based feature selection. Pre-processing able to reduce 50% data dimension. For prediction model development we combine with multiple classification algorithm such as multiclass decision jungle, decision forest, logistic regression and neural network to come out with highest accuracy of N and P detection. We conclude that near infrared spectroscopy combines with feature selection and multiclass classification able to determine nitrogen and phosphorus.
  • Publication
    Estimation of Harumanis (Mangifera indica L.) Sweetness using Near-Infrared (NIR) Spectroscopy
    ( 2020-03-20)
    Sabri, Mohd Shafiq Amirul
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    ; ; ; ;
    Laili M.H.
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    Laili A.R.
    ;
    Ismail M.N.M.
    Harumanis mango quality demanded by consumers is depending on the sweetness level of the fruit. The sweetness is evaluated by brix percentage using refractometer as a representative factor correlated with near-infrared (NIR) spectroscopy spectral absorbance. NIR spectroscopy method of sampling have been tested to overcome the time consuming, complex chemical analysis more importantly invasive sampling methods in order to determine the sugar content in mangoes. Spectral absorbance data from range 941 nm to 1685 nm of mango skin is correlated with Brix reading then tested through five pre-processing techniques. Data calibration and prediction of both data is evaluated using Partial Least Square Regression (PLSR) model. In the final analysis, Unit vector normalization (UVN) technique has achieved as a best pre-processing technique for predicting results, with the coefficient of determination (R2) values of 0.9836 and root mean square error (RMSE) values of 0.3131. Overall, the correlation of NIRS absorbance data and Brix data can be obtained using PLSR model with UVN pre-processing technique. Henceforth, we can conclude that the NIRS method of sampling can be used to identify sugar content in Harumanis mango by using time saving, non-invasive and less laborious method of sampling.
  • 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.
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    Shahimin M.M.
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    Al-Asadi H.A.A.
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    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.