Volume 5, Issue 11, November 2014

Effects of Variation of Injection Current, Differential Gain and Injection Current Efficiency on the Modulation Performance of a GaInP Based 635nm MQW Red Laser

Md. Ashiquzzaman and Kazi Farjana Nasrin

Department of EEE, Faculty of Engineering, Stamford University Bangladesh, Siddeswari, Dhaka-1217, Bangladesh
Department of Customer Care, Banglalink, Gulshan-1, Dhaka-1212, Bangladesh

Abstract– In this work, the effects of variation of Injection Current, Differential Gain and Current Injection Efficiency on the Modulation performance characteristics of a GaInP based 635nm Red laser have been obtained through proper simulation and computations. Here the analyzed red laser consists of 3 multiple quantum well (MQW) and separate confinement heterostructure (SCH). The total simulation process of the designed Ga0.5In0.5P/(Al0.5Ga0.5)0.5In0.5P is completed by using MATLAB software. The injection current is proposed 90mA where the threshold current is maintained 6.7mA at the temperature of 300K. By sustaining the proposed injection current the peak intensity is found at exactly 635nm wavelength with the power of 105mW. A maximum resonance frequency is obtained 10 GHz with the modulation bandwidth of 16.25 GHz. By varying the value of different parameters the total analyses and the performance of the laser has been optimized.

Keywords— Differential Gain, Injection Current, Injection Current Efficiency, Laser Diode and Modulation Response

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Jumps in the Kenyan Interest Rates

Apaka Rangita, Silas N. Onyango, Omolo Ongati and Otula Nyakinda

School of Mathematics and Actuarial Science, Jaramogi Oginga Odinga University of Science and Technology, P.O. Box 210-40601 Bondo, Kenya
KCA University, P.O. Box 56808 Ruaraka, Nairobi

Abstract– In this paper, we use the Bernoulli Jump Diffusion (BJD) process to test for the existence and probability of jumps in the Kenyan interest rates. We test these using the Maximum Likelihood Estimation (MLE) method on the weekly changes in the 91 day Kenyan treasury bills rates. We also compare the BJD process and the Pure Diffusion Process (PDP) in modeling these interest rates. We use the statistical software Eviews 6 to analyze the data.

Keywords— Jumps, Models, Diffusion and Bernoulli

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Minimizing Vibration Effects in Satellite Laser Communication

Shaikhul Arefin Khan and Mohammed Tarique

Department of Electrical and Electronic Engineering, Stamford University, Bangladesh
College of Engineering, Ajman University of Science and Technology-Fujairah Campus, Fujairah, United Arab Emirates

Abstract– A natural development in the space communication is the free space laser communication. The free space laser communication has greater advantage over traditional Radio Frequency (RF) communication. Some of the advantages are high data rate, low probability of detection and minimum interception. The major limitation of this optical communication is the noise introduced by the mechanical vibration of the satellites. This kind of vibration causes pointing problem and affects the performance of the inter-satellite link in terms of bit error rate. Hence a perfect tracking system is required for transmitting and receiving satellite. In this paper, a novel method to improve tracking system has been introduced. It has been shown that the vibration effects can be reduced to an acceptable level and hence the bit error rate can be reduced by using a feed forward compensation technique. The improvement in Bit Error Rate (BER) has also been presented in this paper.

Keywords— Bit Error Rate, Feed Forward Compensation, Laser Link and PID Controller

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Modeling of Multiport Systems via a Mode-Revealing Transformer

Ehsan Elahi, Hamid Keivani and Alireza Alesaadi

Abstract– Employing an admittance matrix in the frequency domain by rational functions for power transformers is a well-known method which improves calculation efficiency. This model must be passive in order to avoid unstable time domain simulations. All of the methods have made efforts to overcome the problem of preserving the passivity of the final model. In this paper a similarity transformation matrix which better reveals the eigenvalues of the admittance matrix is presented. The chosen transformation preserves the passivity and symmetry of the original data.

Keywords— Electromagnetic Transients, Network Equivalent, Passivity Enforcement, Pole-Residue Model and Vector Fitting

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Chitosan Coated Copper-Oxide Film onto Si-wafer: A Novel Photo Catalyst for CO2 Reduction

Srijita Basumallick

Chemistry Department, National Institute of Technology Agartala, Agartala, India

Abstract– We report here synthesis characterization and application of chitosan coated copper-oxide nano catalyst to photo reduction of carbon dioxide. The catalyst was synthesized by one pot hydrothermal method using HCl depolymerized chitosan and CuSO4 penta hydrate salt. The purified catalysts were characterized by FTIR, AFM and XPS. A boron doped Si- wafer was spin coated with a thin film of aqueous dispersions of the catalyst for photo-reduction of CO2. We observed an indication of formation of formic acid in FTIR analysis as photo-reduction product. We conclude combined Si-Wafer and CuxO nano material is a promising photo-catalyst for CO2 reduction.

Keywords— CO2 Reduction, Photo Catalyst and Chitosan Coated–Copper Oxide

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