12908

11809

كارشناسي ارشد

مخابرات(ميدان)

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1396

سيزده، 90ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

ابوالقاسم زيدآبادي نژاد

رضا صفيان

ذاكر حسين فيروزه، احمد بخت افروز

1396/07/24

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID11809

Analysis and Simulation of Diffraction Gratings and Design of Terahertz Polarizer Farzaneh Arab Juneghani farzaneh arab@ec iut ac ir August 29 2017 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor assoc prof Abolghasem Zeidaabadi Nezhad zeidabad@cc iut ac ir Abstract Diffraction grating is a periodic structure which diffracts incident light into several beams in different directions whichdepend on grating period and wavelength of the incident light In the past few years gratings have had different appli cations in optical frequencies but today with the development of technology these structures have various and differentapplications from microwave to optical frequencies Gratings are used in the fabrication of many devices in terahertz suchas polarizer waveguide absorber sensor and etc These structures are based on metal and dielectric or their combination Furthermore in the last two decades with the discovery of graphene as a two dimensional material with special electricaland mechanical properties the gratings based on graphene are investigated and analyzed Initial analysis of gratings goesback to early 20th century Generally analysis methods of gratings can be classified into two categories the integral andthe differential methods The differential and integral methods are based on differential and integral forms of Maxwell sequations respectively Integral methods can be used for any type of gratings without numerical instability Disadvantagesof this method are mathematical complicacy and difficult implementation and comprehension While differential methodsneed simpler mathematical techniques than integral methods but sometimes these methods lead to numerical instabilities Coordinate transformation method or C method and rigorous coupled wave analysis RCWA are two common differentialmethods that are appropriate for relief and lamellar gratings respectively In this thesis multilayer metal and dielectricgratings are analyzed and simulated by C method and rigorous coupled wave analysis and scattering matrix is used tospeed convergence rate also Fourier expansion based on Li s rules is applied for TM polarization in inhomogeneous media Moreover the multilayer relief graphene gratings are analyzed by C method that it is able to analyze deep gratings whileother existed methods for analysis of relief graphene gratings are limited to very shallow gratings Finally a polarizer basedon graphene grating and a wire grid polarizer are designed and simulated by C method and RCWA respectively in terahertzfrequency region Key Words Diffraction grating Coordinate transformation method Rigorous coupled wave analy sis Terahertz Graphene Polarizer

ابوالقاسم زيدآبادي نژاد

رضا صفيان

ذاكر حسين فيروزه، احمد بخت افروز