Metasurfaces: coherent control of light in two dimensions

Abstract

In this thesis, control of light with light without nonlinearity in plasmonic metasurfaces is extended from zero to two spatial dimensions enabling a range of novel applications.
In particular:

For the first time, all-optical logical operations between two-dimensional light distributions are demonstrated based on coherent absorption and coherent transparency of a plasmonic metasurface. XOR, XNOR, AND and OR operations are performed between coherent optical signals of 785 nm wavelength and applied to separate spatially multiplexed optical channels.

Qualitative and quantitative pattern recognition and image analysis are performed for the first time based on the coherent interaction of wavefronts on an absorbing plasmonic metasurface within a hardware-based system at 790 nm wavelength.

All-optical control of focusing of light is realized by superimposing Fresnel zone patterns on an absorbing metasurface using coherent light for the first time. Switching of focal intensity, depth, diameter and distance and effective replacement of a lens by an aperture are accomplished by optical phase modulation at 790 nm wavelength without moving parts.

The first imaging interferometer for spatially resolved control of absorption of light with light in plasmonic metasurfaces was built for this thesis. Using coherent light, two spatial intensity distributions (inputs) are imaged on a free-standing gold metasurface and their interaction (output) is monitored by an imaging detector. Measurements show that the system's spatial resolution is about 900 nm.

Two-dimensional control of light with light on plasmonic metasurfaces is in principle compatible with quantum regime intensities and 100 THz bandwidth. Therefore, the presented scheme could provide efficient all-optical wavefront manipulation, computing, imaging and focusing components for future coherent photonic devices and networks.

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Identifiers

ORCID for Maria Papaioannou: orcid.org/0000-0002-5078-0514

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

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