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Identifier

000451990

Title

Ultrafast THz optical modulation with 2D-material-based device

Alternative Title

Εξαιρετικά γρήγορη οπτική διαμόρφωση τεραχέρτζ με συσκευή βασισμένη σε δυσδιάστατα υλικά

Author

Κυριάκου, Ευδοκία

Thesis advisor

Τζωρτζάκης, Στυλιανός

Reviewer

Κιοσέογλου, Γεώργιος
Καφεσάκη, Μαρία

Abstract

Terahertz (THz) radiation technology aims to bridge the realms of electronics and photonics, and therefore it attracts increasing attention over the last two decades. A developing field of applications is that of THz wireless communication systems, particularly within the landscape of the fast-emerging 5G and 6G technologies, where THz waves promise increased bandwidths for the data demanding systems. Therefore, there is a constantly growing demand for efficient modulators that will operate at THz frequencies, with compact size. Under this prism, two-dimensional (2D) materials such as graphene, hold great promise and have sparked widespread interest in the photonics community due to its unique structure and its unprecedented optoelectronic properties In this master thesis, graphene is investigated as an efficient non-linear material that can be incorporated in modulation devices that operate at THz frequencies. An electrically gate-tuned graphene-based Salisbury screen device is investigated, which consists of a graphene layer, placed on an ionic liquid substrate, back-plated by a metallic back- reflector. We demonstrate that the absorption and phase characteristics of the device can be self-modulated when the intensity of the incident THz field is high enough to drive the graphene layer in the non-linear regime. An amplitude modulation of more than three orders of magnitude in the resonant absorption of our device, and an absolute phase modulation of 130o when the THz field strength increases from 102 to 654 kV/cm is demonstrated. The origin of this nonlinear response is explained by the graphene hot carriers’ dynamics. Beyond telecommunications, such devices could find applications in future dynamically modulated flat optics devices, as well as for THz beam spatio-temporal modulation.

Language

English

Subject

Graphene

Reflectivity

Ανακλαστικότητα

Γραφένιο

Διαμορφωτής

Issue date

2022-11-23

Collection

School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Post-graduate theses