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Broadband, polarization-insensitive, and wide-angle optical absorber based on fractal plasmonics
, Article IEEE Photonics Technology Letters ; Volume PP, Issue 99 , 2016 ; 10411135 (ISSN) ; Abdollahramezani, S ; Chizari, A ; Khavasi, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this paper, a plasmonic absorber consisting of a metal-dielectric-metal stack with a top layer of Sierpinski nanocarpet is theoretically investigated. Such a compact absorber depicts broadband angle-independent behavior over a wide optical wavelength range (400 700 nm) and a broad range of incidence angles (0 80). Including several feature sizes, such a fractal-like structure shows average simulated extinction response of 0:85 for either transverse electric or magnetic polarization states under normal incidence. Underlying mechanisms of absorbance due to excited surface plasmon modes as well as electric/magnetic dipole resonances are well revealed by investigating electric field, magnetic...
Design and Simulation of Electromagnetic Wave Broadband Absorbers Using Metallic and Graphene-based Structures Based on Circuit Theory
, M.Sc. Thesis Sharif University of Technology ; Khavasi, Amin (Supervisor) ; Rejaei, Behzad (Co-Advisor)
Abstract
In this dissertation, we design and simulate Electromagnetic (EM) wave absorbers using periodic array of ultra-thin metallic ribbons, metallic disks and graphene disks based on circuit theory. The equivalent circuit for EM structures significantly eliminates the requirement of systems with advanced hardwares. Firstly, we categorize the metallic absorbers in the literature in two types: narrowband absorbers and broadband absorbers. Surface plasmon polariton, magnetic resonance, interference theory and localized surface plasmon are employed to illustrate the mechanism behind the narrowband absorption. Therefore, they will be the basis for classifying the narrowband absorbers in this work....
Investigating Frequency, Phase, and Amplitude Singularities in a Hybrid Plasmonic System
, M.Sc. Thesis Sharif University of Technology ; Sadighi Bonabi, Rasoul (Supervisor)
Abstract
In recent years, nanoplasmonic quantum has been an active and developing field, resulting in several quanta and nonlinear qualities in the time-frequency interval, such as the creation of coherent single photons, nonlinear observation in nanometer dimensions, high-speed optical switch, etc. In the meantime, the controlled emission of surface polaritons resulted in the development of new devices such as nanolasers , subwavelength diodes, and high-speed phase and amplitude modulators , all of which have had a significant impact on the development of technology in very miniature dimensions. Numerous approaches have been proposed for the manufacturing of nanolasers, or reinforced plasmon...
A sensitive colorimetric detection of ascorbic acid in pharmaceutical products based on formation of anisotropic silver nanoparticles
, Article Scientia Iranica ; Volume 17, Issue 2 F , 2010 , Pages 148-153 ; 10263098 (ISSN) ; Karimi, M. A ; Shahheydari, F ; Sharif University of Technology
2010
Abstract
A sensitive colorimetric method for the detection of ascorbic acid was proposed in this research based on the reduction of silver ions by ascorbic acid in the presence of citrate-stabilized silver seeds, additional trisodium citrate and a polymer such as polyvinylpyrrolidone. The color of the stable sol is controlled by varying the concentration of trisodium citrate (TSC), polyvinylpyrrolidone, silver nitrate and silver seeds. The reduction of Ag + to triangle silver nanoparticles (Ag-NPs) by ascorbic acid in the presence of trisodium citrate (TSC) and silver seeds produced two very intense surface plasmon resonance peaks of Ag-NPs. The plasmon absorbance of Ag-NPs allows the quantitative...