Controlling light with photonic metamaterials

Abstract

This thesis reports on my research efforts towards controlling light with photonic metamaterials for desired functionalities:

I have demonstrated a new family of continuously metallic metamaterials-‘intaglio’ and ‘bas-relief’ metamaterials. They are formed of indented or raised sub-wavelength patterns with depth/height of the order 100 nm and offer a robust and flexible paradigm for engineering the spectral response of metals in the vis-NIR domains. Controlling the colour of metals by intaglio/bas-relief metamaterials has been realized. I have also demonstrated the concept of ‘dielectric loaded’ metamaterials where nanostructured dielectrics on unstructured metal surfaces work as optical frequency selective surfaces.

I have demonstrated for the first time controlling light with light without nonlinearity using a plasmonic metamaterial. I have experimentally shown that the interference of two coherent beams can eliminate the plasmonic Joule losses of light energy in the metamaterial with thickness less than one tenth of the wavelength of light or, in contrast, can lead to almost total absorption of light. The phenomenon provides functionality that can be implemented freely across a broad visible to infrared range by varying the structural design.

I have demonstrated for the first time that a strong light-driven force can be generated when a plasmonic metamaterial is illuminated in close proximity to a dielectric or metal surface. This near-field force can exceed radiation pressure to provide an optically controlled adhesion mechanism mimicking the gecko toe. I have first demonstrated resonant optical forces which are tens of times stronger than radiation pressure within planar dielectric metamaterials and introduced the concept of optomechanical metamaterials.

An optomechanical metamaterial consisting of an array of dielectric meta-molecules supported on free-standing elastic beams has been designed. It presents a giant nonlinear optical response driven by resonant optomechanical forces and exhibits optical bistability and nonlinear asymmetric transmission at intensity levels of only a few hundred µW/µm2. Furthermore, I have experimentally demonstrated optical magnetic resonances in all-dielectric metamaterials.

I have demonstrated for the first time a non-volatile bi-directional all-optical switching in a phase-change metamaterial. By functionalising a photonic metamaterial with the phase-change chalcogenide glass, phase transitions across a 2000 μm2 area are initiated uniformly by single laser pulse. Reversible switching both in the near- and mid-infrared spectral ranges with a shift of optical resonance position up to 500 nm has been achieved at optical excitation levels of 0.25 mW/μm2, leading to a reflection contrast ratio exceeding 4:1 and transmission contrast around 3.5:1.

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Identifiers

ORCID for Nikolay I. Zheludev: orcid.org/0000-0002-1013-6636

ORCID for K.F. MacDonald: orcid.org/0000-0002-3877-2976

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