Rakibul Hasan Sagor

An optimization method for parameter extraction of metals using modified Debye model

The Modified Debye Model (MDM) parameters for five metals are presented. A nonlinear optimization algorithm has been developed in order to extract the parameters for the metals. The extracted parameters have been used to determine the complex relative permittivity of the metals in optical and near-IR region of electromagnetic spectrum. The obtained results have been compared with the experimental values and an excellent agreement has been found.

Optimization of the optical properties of cuprous oxide and silicon-germanium alloy using the Lorentz and Debye models

The modeling parameters of cuprous oxide (Cu2O) and silicon-germanium (Si-Ge) alloy for the single-pole Lorentz model and the single-pole modified Debye model (MDM) are optimized and presented. A nonlinear optimization algorithm has been developed in order to optimize the parameters such that they are applicable to a wide frequency range. The obtained parameters have been used to determine the complex relative permittivity of the materials and compared with the experimental values. A very good agreement has been observed between the experimental values and the optimized parameters in the case of both the material models. The associated root mean square (RMS) deviations have been found to be as little as 0.15 and 0.08 for the Lorentz model and 0.1638 and 0.3710 for the modified Debye model respectively.

A Genetic Algorithm Based Approach for the Extraction of Optical Parameters

We present the Debye model parameters of four materials which are extensively used in the field of electronics and photonics. The parameters have been extracted using a Genetic Algorithm (GA) based technique. We have determined the complex relative permittivity using the extracted modeling parameters and compared with the experimentally obtained ones. A very good agreement has been found in each case which validates our extracted parameters. The associated root-mean-square (RMS) deviations have been found to be 0.3894, 0.026, 0.8163 and 0.4370 for graphene, graphene oxide, aluminum zinc oxide (AZO) and gallium zinc oxide (GZO) respectively.

Extraction of lorentz model parameters for dielectrics and their application in nanoplasmonics

The Lorentz model parameters for alumina, aluminum arsenide, zinc oxide, potassium bromide, graphene and gallium arsenide are optimized using a nonlinear optimization algorithm based on the Hooke and Jeeves method. The complex relative permittivity of each of the mentioned materials is calculated over a long wavelength range using the optimized parameters. The obtained permittivity curves exhibit very good match with those obtained from the experimental results. The symmetric SPP mode propagation through MDM waveguides containing alumina and aluminum arsenide as dielectric layers sandwiched between layers of silver has been investigated using their optimized modeling parameters.

Characteristics of Symmetric Surface Plasmon Polariton Mode in Glass–Metal–Glass Waveguide

The propagation characteristics of symmetric surface plasmon polariton mode in a glass–metal–glass waveguide are presented. Gallium lanthanum sulfide has been taken as the glass and silver (Ag) has been used as the metal. The analysis has been done both numerically and analytically. A two-dimensional finite-difference time-domain-based simulation model has been developed in order to analyze the propagation characteristics numerically. The obtained results using numerical and analytical methods have been compared and a very good agreement has been found.

Performance Analysis of a Differential Evolution Algorithm in Modeling Parameter Extraction of Optical Material

Determination of accurate modeling parameters of optical materials prior to defining the materials in the simulation model is fundamentally important to obtain simulation results close to the experimental ones. However, extracting modeling parameters of optical materials is inherently difficult because it involves fitting both real and imaginary parts of the relative permittivity using a single set of parameters. In this paper, an evolutionary algorithm called differential evolution (DE) has been utilized to extract the optical modeling parameters of graphene oxide. The performance of DE to find the optimal results has been analyzed by using different objective functions and boundary values. Two objective functions are used out of which one is proposed by us. Root-means-square (RMS) deviation, a measure of accuracy of the numerically obtained results has been determined for each case. From the obtained results it has been found that the DE algorithm extracted the optical modeling parameters successfully with very small RMS deviation for both real and imaginary parts of the complex relative permittivity.

Sudy of PV implemenaion for elecriciy generation in Bangladesh

The goal of this paper is o make effective use of solar energy of Photovoltaic (PV) module so that we can get maximum power output from sunlight. Since the performance of a PV cell depends on maximum efficiency factors, mainly on solar radiation and temperature, this paper examines the performance parameters of PV module for various locations by analyzing twenty-two years average solar radiation data in Bangladesh. To examine the performance parameters, the Solarex MSX60, a typical 60W PV module is chosen. The mathematical model for the chosen module is implemented on Matlab. The result of this paper shows the effects of variation of solar radiation on PV module within Bangladesh. Eventually, his paper proposes suitable locations for implementing solar PV modules based on maximum efficiency within Bangladesh.

Optimization of debye parameters for dielectric materials and investigation of symmetric SPP mode propagation properties in DMD waveguide

The Modified Debye Model (MDM) parameters for Cuprous Oxide (Cu2O) and Silicon-Germanium Alloy (1.5:1) are presented. A nonlinear optimization algorithm has been developed in order to optimize the parameters for the materials. The obtained parameters have been used to determine the complex relative permittivity, which show an excellent agreement with the experimental values. The root-mean-square (RMS) deviations are found to be as little as 0.1638 and 0.3710 respectively. Finally symmetric Surface Plasmon Polariton (SPP) mode propagation properties in a Dielectric-Metal-Dielectric (DMD) waveguide constructed with silver (Ag) and Cu2O have been studied both analytically and numerically for further verification of the obtained MDM parameters.

Numerical Investigation of SPP Propagation at the Nano-scale MDM Waveguides with a Combiner

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP

Variation of Transmission Characteristics with Ring Geometry in Plasmonic Add-Drop Ring Resonators

Plasmonic add-drop ring resonator configurations in the nanometer scale with different geometric shapes for the ring are proposed. Using known material modelling techniques, a simulation model is developed using the finite-difference time-domain (FDTD) method to calculate the transmission efficiency of these structures at different wavelengths. The effect of increasing coupling distance between the input waveguide and ring on the transmission efficiency is also simulated and analyzed. It has been observed that the add-drop ring resonators with round-edge square ring and elliptical ring both show higher transmission efficiency than the common circular ring design. Moreover, increasing the coupling distance causes a significant reduction in transmission efficiency for each design. Analysis of the transmission characteristics of the different geometric configurations will allow us to compare their suitability for use as filters, biosensors and other optical applications.