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Title: Chalcogenide platforms for photonic metamaterials
Author: Piccinotti, Davide
ISNI:       0000 0004 7967 0516
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2018
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Photonic metamaterials - media artificially structured at the nanometre scale - provide extraordinary optical properties not found in nature. In this work I explored opportunities provided by changes of complex optical properties of chalcogenide alloys related to compositional variation and structural phase change to develop switchable and tunable plasmonic and dielectric metamaterials: • I have systematically explored the properties of Bi:Sb:Te across UV to near infrared wavelengths through combinatorial high-throughput mapping techniques for the widest compositional spread reported so far. This study reveals that Bi:Sb:Te has better plasmonic properties than gold at wavelengths below 580 nm and silver below 365 nm; ability to support dielectric (Mie) resonances better than oxides at telecommunication wavelengths beyond 1200 nm; epsilon-near-zero properties across UV to IR wavelengths; sub-unity refractive index (down to 0.7) in the UV and the highest refractive index in the near-IR (up to 11.5 at 1680 nm) reported so far to our knowledge. • I have studied for the first time the plasmonic character of amorphous Bi:Te and developed resonant optical metasurfaces based on this alloy that present strong, period-dependent plasmonic absorption resonances (QMax = 7.5) in the visible range. Furthermore, I have investigated changes of optical properties of this alloy upon structural phase change from amorphous to crystalline phases. • I have studied for the first time channelling of light through nano-hole arrays filled with dispersive low-epsilon chalcogenides. The complex changes in the composite's spectral response depend strongly on the interplay between the dispersion of the optical properties of the plasmonic nanostructure and the low-epsilon medium and lead to increase of transmission over a broad range of plasmonic frequencies. • I have developed the first switchable UV metamaterials that exploits the low refractive index (equal to 1.07 at 245 nm for c-GST) and phase change properties of chalcogenides. In particular, I have shown that laser-induced structural phase transitions can be used to switch quality factors of dielectric resonances (QMax = 15) in metamaterials without affecting their spectral positions.
Supervisor: Zheludev, Nikolai Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available