Controlling electromagnetic waves with active graphene devices

buir.advisorKocabaş, Coşkun
dc.contributor.authorBalcı, Osman
dc.departmentDepartment of Physicsen_US
dc.descriptionAnkara : The Department of Physics and the Graduate School of Engineering and Science of Bilkent University, 2015.en_US
dc.descriptionThesis (Doctor's) -- Bilkent University, 2015.en_US
dc.descriptionIncludes bibliographical references (leaves 122-130).en_US
dc.descriptionCataloged from PDF version of article.
dc.description.abstractThe dynamic control of electromagnetic waves forms the basis of modern communication technologies. Although sources of microwaves can be controlled by electrical means, the active control of microwaves in the free space has been a challenge due to the lack of an active material. Graphene, the 2-dimensional crystal of carbon, provides a unique platform to control light-matter interaction in a broad spectrum. This thesis describes a new approach to control microwaves using large area active graphene devices. Our strategy relies on electrostatic tuning of the density of high mobility charge carriers on an atomically thin graphene electrode which operates as a tunable metal in microwave frequencies. We developed a method to synthesize large area graphene (20x20 cm2) by chemical vapor deposition. Using large area graphene electrodes, we demonstrate a new class of active surfaces capable of real-time electrical control of reflection, transmission, and absorption of microwaves over a broad spectrum. These active devices allow us to fabricate electrically tunable microwave surfaces such as switchable radar absorbing surfaces and tunable metamaterials with modulation depth of 50𝑑𝐵 and operation voltage of 3𝑉. Large modulation depth, simple device architecture, and mechanical flexibility are the key attributes of the graphene-enabled active microwave surfaces that could find a wide range of applications ranging from active signal processing to adaptive camouflage.
dc.description.statementofresponsibilityby Osman Balcıen_US
dc.format.extentxxiv, 130 leaves : illustrations, charts, photographs ; 30 cm.en_US
dc.publisherBilkent Universityen_US
dc.subjectMicrowave modulator
dc.subjectRadar absorbers
dc.subjectActive metadevices
dc.titleControlling electromagnetic waves with active graphene devicesen_US
dc.title.alternativeElektromanyetik dalgaların aktif grafen aygıtları ile kontrol edilmesi
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