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Design and Implementation of Near Field Excitation System for Spectroscopy of Biological Species
, Ph.D. Dissertation Sharif University of Technology ; Rashidian, Bizhan (Supervisor) ; Vossoughi, Manouchehr (Supervisor) ; Shahrokhian, Saeed (Co-Advisor)
Abstract
The main goal of this project is analysis, design and implementation of scanning near field optical system for detection of biological species. The activities fall in two main category. Theoretical and experimental. In theoretical part, after studying different models describing near field interaction, we have developed software for computationally analysis of nonlinear interaction of light with nanostructures, considering third order nonlinear susceptibility and dispersion behavior of permittivity for metallic nanostructures. The software implements three dimensional finite difference time domain (FDTD) method for analysis of interaction of electromagnetic wave with matter. In developed...
Fluorescent microscopy using localized excitation source with gold nanotriangles: A computational study
, Article Photonics and Nanostructures - Fundamentals and Applications ; Volume 9, Issue 3 , 2011 , Pages 219-224 ; 15694410 (ISSN) ; Rashidian, B ; Vossoughi, M ; Sharif University of Technology
2011
Abstract
A new method for fluorescent microscopy has been proposed. Proposed method uses indirect excitation of fluorophores with nanometer localized illuminating source. Localized source is created at corners of gold nanotriangles which are deposited on glass substrate. Actually the combination of gold nanotriangle (deposited on glass) acts as active substrate (where species will be placed) for our proposed method. The structure will be scanned with a focused beam of laser (or combination of beams). Due to electric field enhancement in corners and edges of nanotringle (because of surface plasmons), third order nonlinear effect will be enhanced accordingly. Enhancement in third order nonlinearity...
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...