12735

1050 دكتري

دكتري

مخابرات - ميدان

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1396

[هفده]، [119]ص.: مصور، جدول، نمودار(رنگي)

ص.ع. به فارسي و انگليسي

ابوالقاسم زيدآبادي نژاد، محمود شاه آبادي

امير برجي

عباس بهجت، ذاكر حسين فيروزه، احمد بخت افروز

1396/06/07

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID1050 دكتري

1 Diffraction Analysis of Plasmonic Nanostructures Hoda Fadakar h fadakar@ec iut ac ir July 5 2017 Doctor of Philosophy Thesis Department of Electrical and Computer EngineeringIsfahan University of Technology Isfahan 84156 83111 IranSupervisor Dr Abolghasem Zeidaabadi Nezhad zeidabad@cc iut ac ir Supervisor Prof Mahmoud Shahabadi shahabad@ut ac ir Advisor Dr Amir Borji aborji@sharif eduDepartment Graduate Program Coordinator Dr Mohammadreza Taban Isfahan University of Technology Isfahan 84156 83111 Iran University of Tehran Tehran 1439957131 Iran Sharif University of Technology Tehran 14588 89694 Iran AbstractTransmission line formulation TLF is used to analyze two dimensional low loss metallic gratings at opticalfrequencies when plasmonic waves can propagate in the structure This method like any other Fourier basedmethod suffers from numerical instabilities when applied to such structures A systematic approach toavoid these instabilities is proposed in this research These numerical artifacts are attributed to the violationof the so called Li s inverse rule and the appearance of higher order spurious modes A new approach isproposed to identify and to greatly reduce the effect of these spurious modes based on the degree to whichthese modes satisfy conservation of momentum Furthermore periodically patterned graphene sheets PPGS embedded in planar multilayered media is modeled using TLF Moreover the numerical convergence can beslow because of the fact that the conductivity is zero in un lled areas of the patterned surface where Li sinverse rule is not applicable A simple and ef cient approach is proposed to overcome this problem suchthat the exact boundary condition can be applied and the surface current density on PPGS can be obtainedaccurately Fast convergence and accuracy of the method will be demonstrated by computing the absorptionof PPGS Moreover the proposed method is utilized to design a wideband tunable wide angle polarizerconsisting of two parallel PPGS separated by a 0 5 m layer of SiO2 For the nal stage of this researchand as an alternative to PPGS we introduce a layer of randomly positioned spherical nano particles withthe capability of being used in various optical applications Here we investigate the impact of such layerof silver nano spheres on the absorption ef ciency of thin lm silicon solar cells The Coherent PotentialApproximation CPA is used for the required computations The metallic array of nano spheres is assumedto be embedded inside the active layer of the solar cell The formulation to compute the absorbed powerby ordered perfectly periodic and disordered arrays of nanospheres embedded inside the lossy backgroundis provided It is shown that the disorder can considerably enhance light trapping and absorption Higherdisorder allows for more ef cient diffraction and leads to wider bandwidth of optical absorption Key Words Metallic grating periodically patterned graphene sheets transmission line formulation dis ordered array of plasmonic nanoparticles coherent potential approximation

ابوالقاسم زيدآبادي نژاد، محمود شاه آبادي

امير برجي

عباس بهجت، ذاكر حسين فيروزه، احمد بخت افروز