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Identifier

000467052

Title

Polarization-resolved second and third harmonic generation in 2D materials

Alternative Title

Γέννηση δεύτερης και τρίτης αρμονικής με εξάρτηση από την πόλωση σε δισδιάστατα υλικά

Author

Μαραγκάκης, Γεώργιος Μιλτιάδης Ε.

Thesis advisor

Στρατάκης, Εμμανουήλ

Reviewer

Κιοσέογλου, Γεώργιος
Μακρής, Κωνσταντίνος
Κομίνης, Ιωάννης
Κοπιδάκης, Γεώργιος
Λυμπεράκης, Λυβέριος
Πελεκάνος, Νικόλαος

Abstract

In this PhD thesis, second and third harmonic generation (SHG, THG) produced by 2D materials, when they interact with laser field, are explored. By employing laser-scanning using galvanometric mirrors, spatially resolved SHG or THG intensities, forming images, are recorded, while rotating the linear polarization of the excitation laser field, performing polarization-resolved SHG or THG (P-SHG, P-THG) microscopy imaging. The experimental data are then fitted with equations based on suitable nonlinear optics models. The demonstrated methods are all-optical, large-area, minimally-invasive and rapid. In the first work (Chapter 2), P-SHG imaging in an atomically thin WS₂ crystal is performed, which belongs to the transition metal dichalcogenides (TMDs). Information on the crystallographic direction distribution is revealed, and the superiority of a P-SHG analysis over intensity-only SHG measurements is experimentally demonstrated. In the second work (Chapter 3), a nonlinear optical imaging technique is presented, based on SHG microscopy and a SHG interference model, to map in a WS₂/MoS₂ 2D TMD heterostructure the twist angle, i.e., the relative orientation between the constituent monolayers. In the third work (Chapter 4), the P-SHG properties of ultrathin tin(II) sulfide (SnS) crystals are investigated. SnS exhibits in-plane anisotropic response, offering an additional degree of freedom in manipulating its properties. The armchair/zigzag crystallographic directions of several 2D SnS crystals belonging in the same field of view are calculated, as well as the relative magnitudes of the tensor components of the second-order nonlinear optical susceptibility.

Language

English

Subject

In-plane anisotropic response

Multiphoton microscopy imaging

Πολυφωτονική μικροσκοπία απεικόνισης

“Εντος-του-επιπέδου” (in-plane) ανισοτροπική απόκριση

Issue date

2024-09-09

Collection

School/Department--School of Sciences and Engineering--Department of Physics--Doctoral theses

Type of Work--Doctoral theses