15766

14075

كارشناسي ارشد

مخابرات (ميدان)

اصفهان : دانشگاه صنعتي اصفهان

1399

سيزده، 71ص. : مصور(رنگي)، جدول، نمودار

ذاكر حسين فيروزه، رضا صفيان

احمد بخت افروز، محسن مداح علي

1399/06/30

كتابنامه

مهندسي برق

مهندسي برق و كامپيوتر

1399/06/31

2634421

Bandwidth Optimization for Mach Zehnder Electro Optic Modulators Zobeyde Dadkhah z dadkhah@ec iut ac ir Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Assoc Prof Zaker Hossein Firouzeh zhfirouzeh@iut ac ir Supervisor Assist Prof Reza Safian rsafian@iut ac ir Abstract Today more than ever the application of the Internet has affected human s life Therefore it isessential to increase the capacity of telecommunication in order to transmit large amount of data Op tical modulators in these systems are responsible to convert low frequency data into optical signals fordata transmission enhancement In past years many materials have been used such as dielectric crys tal organic nonlinear optical materials semiconductors graphene and plasmonic effect When lightpasses through dielectric crystal like lithium niobate and also is exposed by an electrical field the lightis modulated Mach Zehnder structure using lithium niobate have simple fabrication process highextinction ratio and wide bandwidth that is also commercially attractive High switching voltage andlonger phase shifter length are the main challenges The purpose of this thesis is to design a lithiumniobate modulator that is easier for fabrication in comparison with previous works Moreover thebandwidth switching voltage and extinction ratio are acceptable compared to prior structures Of theformer researches that exhibited high performance is the use of etched lithium niobate waveguide ontop of a thin film lithium niobate Such a waveguide has optical loss due to metal electrodes For thisreason we can place signal electrode and ground electrode at the shortest distance from each other Asa result the electrical field which is between the two electrodes becomes stronger The modulationon the waveguide that is placed between two electrodes increases Vswitching L decreases switchingvoltage decreases and in some cases bandwidth increases However lithium niobate has a crystallianstructure the fabrication of such a waveguide is more expensive and complicated Thus there is aneed for a waveguide that has low optical loss due to metal electrodes simple fabrication and inex pensive material In this work silicon is used to solve the above problems The designed waveguideis a hybrid structure including silicon thin film lithium niobate silicon Based on the aforemen tioned hybrid waveguide we designed three modulators that have the lowest optical loss due to metalelectrodes and bending loss consequently the lowest Vswitching L among similar modulators Fur thermore because of the lowest Vswitching L the modulator lunches with very low voltage Sincemodulators are designed with a silicon substrate they are also compatible to CMOS circuits

ذاكر حسين فيروزه، رضا صفيان

احمد بخت افروز، محسن مداح علي