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Analysis and Test of Magnetic Behavior of Special Materials and its Nano Scaling Behavior
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
In the first part of this thesis, limitations on magnetic field distribution are studied. After that methods of creating high gradient magnetic field and limitations on it is discussed. In the second part, magnetic properties of materials and the effect of particle shape and size on these properties are studied. In this part a comprehensive analysis on demagnetizing field inside magnetic bodies is also conducted and its dependence on material susceptibility and shape is discussed. At the end of this part the effect of particle shape and size on its hysteresis loop is demonstrated theoretically, practically and by computer simulation. In order to ...
Weak Convergence of Approximation of American Option Price
, M.Sc. Thesis Sharif University of Technology ; Zohouri Zangeneh, Bijan (Supervisor)
Abstract
In some pricing methods like European Option Price there are some deterministic exercise times but in American Option Price it is Stochastic Process. So, it would be very difficult to calculate the exact formula for it. So, we can use some approximation for this goal. The main purpose of the thesis is to consider of weak convergence for a special approximation
Analysis of third harmonic generation and four wave mixing in gold nanostructures by nonlinear finite difference time domain
, Article Journal of Nanoscience and Nanotechnology ; Volume 10, Issue 11 , 2010 , Pages 7179-7182 ; 15334880 (ISSN) ; Shahmansouri, A ; Rashidian, B ; Sharif University of Technology
2010
Abstract
Third order nonlinear effects and its enhancement in gold nanostructures has been numerically studied. Analysis method is based on computationally solving nonlinear Maxwell's equations, considering dispersion behavior of permittivity described by Drude model and third order nonlinear susceptibility. Simulation is done by method of nonlinear finite difference time domain method, in which nonlinear equations of electric field are solved by Newton-Raphshon method. As the main outcomes of third order nonlinear susceptibility, four wave mixing and third harmonic generation terms are produced around gold nanostructures. Results of analysis on different geometries and structures show that third...
CVD synthesis of small-diameter single-walled carbon nanotubes on silicon
, Article Scientia Iranica ; Volume 16, Issue 1 D , 2009 , Pages 61-64 ; 10263098 (ISSN) ; Sasanpour, P ; Rashidian, B ; Sharif University of Technology
2009
Abstract
A simple process for the chemical vapor deposition of ultra SD single-wall carbon nanotubes has been developed. In this process, an iron nitrate nonahydrate solution in isopropyl alcohol with a concentration of (400 μgr/milt) was used to catalyst nanoparticle formation on an oxidized silicon wafer. The oxide on the substrate was made of a thick layer of wet oxide sandwiched between two thin layers of dry oxide. The process results in semiconducting Single-Walled carbon Nano Tubes (SWNTs) with diameters of less than 0.7 nm and more than a 1 ev band gap energy, which are amongst the smallest diameters of SWNTs ever reported. © Sharif University of Technology, June 2009
A quantum description of linear, and non-linear optical interactions in arrays of plasmonic nanoparticles
, Article Journal of Modern Optics ; Volume 65, Issue 10 , 2018 , Pages 1235-1244 ; 09500340 (ISSN) ; Ahmadi, Z ; Rashidian, B ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
A quantum theory for describing the interaction of photons and plasmons, in one- and two-dimensional arrays is presented. Ohmic losses and inter-band transitions are not considered. We use macroscopic approach, and quantum field theory methods including S-matrix expansion, and Feynman diagrams for this purpose. Non-linear interactions are also studied, and increasing the probability of such interactions, and its application are also discussed. © 2018 Informa UK Limited, trading as Taylor & Francis Group
Design and Fabrication of Tip for a Nanolithography System
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
Various applications of nanostructures in electronics, optoelectronics, MEMS, photonics and plasmonic make their fabrication an interesting research topic recently. Progress in nanotechnology depends on the capability to fabricate, position and interconnect nanometer-scale structures. The development of fabrication devices with nanoscales is mainly dependent on the existence of a suitable nanolithography approach. Patterning materials with nanoscale features aimed at improving integration and device performance faced several challenges. The limitation of conventional lithography systems including resolution related issues, operational costs and lack of flexibility to pattern organic and...
Photothermal heating using a near-field plasmonic probe, application in NFO-CVD
, Article 5th International Conference on Millimeter-Wave and Terahertz Technologies, MMWaTT 2018, 18 December 2018 through 20 December 2018 ; Volume 2018-December , 2019 , Pages 94-96 ; 21570965 (ISSN); 9781538677179 (ISBN) ; Heydarian, H ; Rashidian, B ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
We present near-field photothermal heating capability of an aperture SNOM probe by exploiting a bowtie nanostructure on top of the probe aperture, which operates as a nanosource of heat to activate underlying nanoparticle. Heat generation density calculated for the bowtie nanostructure at its absorption resonance wavelength of 694 nm verifies efficient concentration of heating power at the bowtie tips, due to optical near-field effects. Total absorbed power for the nanodisk beneath the probe has the same resonance wavelength at 694 nm, which confirms that the temperature increase produced at the underneath nanoparticle is due to utilizing the bowtie nanostructure on top of the SNOM probe as...
Modal control of thermoplasmonic behavior of nanostructures based on excitation of perfect absorption resonances
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 37, Issue 8 , 2020 , Pages 2238-2247 ; Heydarian, H ; Rashidian, B ; Sharif University of Technology
OSA - The Optical Society
2020
Abstract
Controlling the localized heat generation density and temperature profile of nanostructures exploiting perfect absorption of individual resonance modes is reported. The methodology is applied to spherically symmetric nanostructures using the T-matrix method. It is demonstrated that perfect modal splitting of the absorption power at desired wavelengths and individual excitation of the modes provide the ability to localize the generated heat at desired locations, and control the resulting temperature profile in multilayer core–shell structures. By knowing the thermal behavior of individual modes, it is shown that excitation of the perfect absorption modes at desired temperatures can result in...
Legendre polynomial expansion for analysis of linear one-dimensional inhomogeneous optical structures and photonic crystals
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 23, Issue 5 , 2006 , Pages 969-977 ; 07403224 (ISSN) ; Mehrany, K ; Rashidian, B ; Sharif University of Technology
Optical Society of American (OSA)
2006
Abstract
A Legendre polynomial expansion of electromagnetic fields for analysis of layers with an inhomogeneous refractive index profile is reported. The solution of Maxwell's equations subject to boundary conditions is sought in a complete space spanned by Legendre polynomials. Also, the permittivity profile is interpolated by polynomials. Different cases including computation of reflection-transmission coefficients of inhomogeneous layers, band-structure extraction of one-dimensional photonic crystals whose unit-cell refractive index profiles are inhomogeneous, and inhomogeneous planar waveguide analysis are investigated. The presented approach can be used to obtain the transfer matrix of an...
Analysis of Parameters Affecting the Behavior of Frequency Selective Devices and their Scaling to Nano Regimes
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bijan (Supervisor)
Abstract
In this project, different types of optical frequency selector devices are compared with each other and the factors limiting their behavior (losses, throughput, quality factor, etc.) are precisely analyzed. Change this behavior in near-field and far-field scales as well as the behavior of these devices in nano-dimensions are analyzed. Also, the main theoretical and technological limitations of different types of optical filters in far-field and near-field regimes are compared. In the following, the scaling behavior of different filter families in passing to nanometric dimensions is investigated and finally the limitations of the possibility of making the selected sample are analyzed. For...
Hermite polynomial expansion for analysis of electromagnetic slow waves in coupled nano conducting layer with Gaussian profile
, Article LAPC 2007: 3rd Loughborough Antennas and Propagation Conference, Loughborough, 2 April 2007 through 3 April 2007 ; 2007 , Pages 265-268 ; 1424407761 (ISBN); 9781424407767 (ISBN) ; Mehrany, K ; Rashidian, B ; Sharif University of Technology
2007
Abstract
The possibility of electromagnetic slow wave propagation in dielectric slab waveguides, when free two-dimensional interface charge layers are generated at film-substrate and film-cover interfaces, is already explored. In this paper, the propagation of electromagnetic slow waves supported by induced charge layers of nonzero thickness, whose induced charge densities have Gaussian profiles, is investigated for the first time. In order to analyze the effects of inhomogeneity in the conductivity profile, the electric field is expanded in terms of Hermite polynomials and each eigenmode is sought in the complete space spanned by them. © 2007 IEEE
Monitoring of Ion Implanter Radiation
, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bizhan (Supervisor)
Abstract
X-ray radiation is an ionizing radiation that can be produced under some conditions in an ion implanter and can have significant effects on equipment and personnel health. In this dissertation, we first examine the properties of ionizing radiations and their effects of electronic devices and discuss the general properties of common detectors. Next, Using Silvaco TCAD and GEANT4 we will simulate the interaction of ionzing radiation with energies up to 300 keV with electronic devices including a commercial off the shelf photo diode and a specialized x-ray detector and show that these devices can efficiently reveal informations of a radiation source to the user. Also, it has been shown that...
Three-dimensional diffraction analysis of gratings based on Legendre expansion of electromagnetic fields
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 24, Issue 10 , 2007 , Pages 2676-2685 ; 07403224 (ISSN) ; Mehrany, K ; Rashidian, B ; Sharif University of Technology
Optical Society of American (OSA)
2007
Abstract
Three-dimensional vectorial diffraction analysis of gratings is presented based on Legendre polynomial expansion of electromagnetic fields. In contrast to conventional rigorous coupled wave analysis (RCWA) in which the solution is obtained using state variables representation of the coupled wave amplitudes, here the solution of first-order coupled Maxwell's equations is expanded in terms of Legendre polynomials, where Maxwell's equations are analytically projected in the Hilbert space spanned by Legendre polynomials. This approach yields well-behaved algebraic equations for deriving diffraction efficiencies and electromagnetic field profiles without facing the problem of numerical...
Comprehensive simulation of the effects of process conditions on plasma enhanced chemical vapor deposition of silicon nitride
, Article Semiconductor Science and Technology ; Volume 23, Issue 9 , 22 August , 2008 ; 02681242 (ISSN) ; Ilati, H ; Rashidian, B ; Sharif University of Technology
2008
Abstract
A numerical model for the deposition of silicon nitride using silane and ammonia mixture in a radio frequency plasma reactor has been developed. Plasma enhanced chemical vapor deposition process is simulated by combined analysis for the glow discharge, fluid flow and chemical reactions. The main goal is to investigate the effect of variations of the process parameters on the deposition rate, and uniformity of the resulting layer. The approach used is based on the theoretical partial differential equation models, without any empirical approximation of the critical data being used. Owing to the fact that the relevant equations are highly nonlinear, the discretization method is of great...
Controlled optical near-field growth of individual free-standing well-oriented carbon nanotubes, application for scattering SNOM/AFM probes
, Article Nanophotonics ; Volume 11, Issue 21 , 2022 , Pages 4671-4686 ; 21928614 (ISSN) ; Heydarian, H ; Rashidian, B ; Sharif University of Technology
De Gruyter Open Ltd
2022
Abstract
Exploiting localized heat-generation density and the resulting enhanced temperature-rise for controlled growth of carbon nanotubes (CNTs) is reported, and its potentials for batch-production of high-quality CNT probes are demonstrated. Optical near field chemical vapor deposition (ONF-CVD) benchtop fabrication schemes are developed for the localized integration of individual well-aligned carbon nanotubes without bending/buckling exactly at desired nanoscale sites. It is demonstrated that generating self-aligned catalyst nanoparticles superimposed on top of silicon nanotips, along with near-field induced absorption confinement, provide the ability to localize the generated heat at the...
Surface electromagnetic waves on dielectrics with conductive interface
, Article Aplications of Photonic Technology, Quebec City, 1 June 2002 through 6 June 2002 ; Volume 4833 , 2002 , Pages 776-782 ; 0277786X (ISSN) ; Khorasani, S ; Rashidian, B ; Sharif University of Technology
2002
Abstract
In several recent papers, layered waveguide structures with conductive interfaces have been discussed, whose propagation properties are controlled by a transverse voltage. These structures can be used as a dynamic optical read/write memory cell, and programmable optical diffractive element. In this paper, the excitation of surface waves with the presence of interface charges is discussed. Interface charges affect the dispersion of surface waves, and therefore they can be used in various applications such as optical modulators, switches, sensors and filters. These waves can be superior to surface plasmon waves since they are not lossy. The lossless property is satisfied in limited range:...
Design and analysis of the integrated plasma wave micro-optical modulator/switch
, Article Fiber and Integrated Optics ; Volume 21, Issue 3 , 2002 , Pages 173-191 ; 01468030 (ISSN) ; Nojeh, A ; Rashidian, B ; Sharif University of Technology
2002
Abstract
Feasibility of a new integrated amplitude modulator/switch operating up to the visible spectrum, based on the absorption of light due to the linear interaction of the incident laser and a two-dimensional plasma layer is demonstrated. Plasma layers are generated via the Muller effect at the waveguide's interfaces. A plasma wave is excited in the two-dimensional gas when it is illuminated by electromagnetic radiation. Thus, due to the energy transfer from the electromagnetic wave to the plasma wave, the output light intensity can be controlled. The device is capable of amplitude modulation of guided beams in dielectric waveguides. Analysis based on both full-classical and semiclassical...
Surface wave excitation control by using interface conductivity on one-dimensional photonic crystals
, Article Novel Optical Systems Design and Optimization V, Seatle, MA, 9 July 2002 through 9 July 2002 ; Volume 4768 , 2002 , Pages 170-175 ; 0277786X (ISSN) ; Khorasani, S ; Rashidian, B ; Sharif University of Technology
2002
Abstract
In several recent papers, layered waveguide structures with conductive interfaces have been discussed, whose propagation properties are controlled by a transverse voltage. These structures have wide range of applications. In this paper, surface wave excitation on one-dimensional photonic crystals at the presence of interface conductivity is discussed. It is shown that excitation of electromagnetic surface waves can be controlled by the interface conductivity. This property can be used in constructing miscellaneous optical devices such as optical modulators, switches and tunable optical filters. Devices based on these waves can be superior to surface plasmon waves since they are not lossy....
Dynamics of interface traps in bonded silicon wafers
, Article Semiconductor Science and Technology ; Volume 17, Issue 5 , 2002 , Pages 421-426 ; 02681242 (ISSN) ; Motieifar, A ; Rashidian, B ; Sharif University of Technology
2002
Abstract
In this paper, a time-domain nonlinear model is proposed for quantum dynamics of interface traps, based on the thermionic emission model. The model is simplified for the interface traps of the directly bonded silicon wafers. This model has been linearized, resulting in an equivalent electrical circuit that has one capacitive and one resistive branch. We discuss the experimental verification of the predicted frequency response on directly bonded n-type silicon wafers. This method enables us to precisely measure the occupation time constant of the interface traps through the recombining electrons from the conduction band, by measuring the frequency response of the interface
Variational approach for extraction of eigenmodes in layered waveguides
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 19, Issue 9 , 2002 , Pages 1978-1981 ; 07403224 (ISSN) ; Khorasani, S ; Rashidian, B ; Sharif University of Technology
Optical Society of America (OSA)
2002
Abstract
A new variational approach to the extraction of guided and leaky modes in layered waveguides is proposed. To verify the method we compare the results of analysis of a typical test case and those from other references and find them in agreement. The efficiency of the proposed approach is compared with that of other reported methods. © 2002 Optical Society of America