تحليل ساختارهاي متناوب مبتني بر گرافن در حضور ميدان مغناطيسي

چكيده انگليسي :

Analysis of Graphene based Periodic Structures in Presence of Magnetic Field Parisa Karimi Khoozani p karimi@ec iut ac ir September 13 2016 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Assist Prof Mohsen Maddah Ali maddahali@cc iut ac ir Co Supervisor Prof Mahmoud Shahabadi shahabad@ut ac ir Abstract Graphene is a 2D material which is consisted of carbon atoms arranged in hexagonal lattice and because of special elec trical thermal and mechanical characteristics is attracted a lot of attention in recent years Graphene due to the supportingsurface plasmons propagation is used in design and fabrication of many microelectronic and nanoelectronic devices suchas waveguides transistors filters absorbers and antennas in terahertz Most impoatant feature of graphene in comparisonto metals is its tunability The surface conductivity of graphene is tunable with the aid of electric bias field and on theother hand it turns into tensor in the precense of static magnetic field For this reason graphene shows gyrotropic andnonreciprocity effects and causes Faraday rotation in transmitted wave The nonreciprocity of graphene can be used indesign of circulators and isolators Faraday rotation is almost independent of frequency in microwave and is about of a fewtens of degrees On the other hand it is low in terahertz and increasing of it is a challenge in this area Using graphenein design of different devices needs to suitable numerical methods for its analysis There are two ways for graphene mod eling In the first way graphene is considered as a dielectric by very small thickness This method needs to fine meshingwhich increased the requirement memory and simulation time and so it is not suitable from point of view of computationalresources In the second way the thickness of graphene is assumed zero and effect of graphene is taken into account inboundary conditions In the present most of commercial EM solvers cannot analyze magnetically biased graphene whilethe others model the graphene using dielectric approach Using graphene in periodic structures can be result in design oftunable devices for controling the reflection transmission and polarization of electromagnetic waves Therefore in thisthesis for the first time a transmission line formulation which is a Fourier based numerical method is used to diffractionanalysis of magnetically biased periodic structures To increase convergence rate true Fourier expansion which is inverserule is recognized based on Li s factorization rules The surface conductivity is zero in some area of unit cell and the trueFourier expansion is not applicable So the approximate boundary condition which is proposed for analysis of unbiasedgraphene arrays is expanded Using the implemented numerical method some of available structures in papers are simu lated to verify the high accuracy and speed of method Moreover a wideband absorber is designed and simulated by thismethod The high attention is devoted to analyze Faraday rotation effect and its challenges in terahertz regime In accord ing with the applications of Faraday rotation and its challenges more exact investigation and exploiting new structures toincrease this effect are proposed for future researches Key Words 1 Graphene 2 Plasmonics 3 Transmission Line Formulation 4 Periodic Structures 5 Non reciprocal Devices 6 Faraday Rotation

كريمي خوزاني، پريسا

تحليل ساختارهاي متناوب مبتني بر گرافن در حضور ميدان مغناطيسي

پلاسمونيك , روش فرمول بندي خط انتقال , افزاره هاي نا همپاسخ , چرخش فارادي