Chalcogenide-based phase-change metamaterials for all-optical, high-contrast switching in a fraction of a wavelength

Abstract

To realise the significant performance gains to be made from all-optical data processing, compact, rapid and high modulation contrast devices need to be produced that can rapidly change their refractive index and absorption1. Phase-change metamaterials are an amalgamation of two existing material concepts to provide new optical functionalities in a single planar device less than 100 nm thick (see figure). The phase-change layer is typically a chalcogenide glass (Ge₂Sb₂Te₅) that can be optically switched between two phases: crystalline and amorphous. The layer will remain in either of these states until it is switched again, providing a reversible 'memory' effect. The metamaterial layer consists of repeating unit cells of asymmetric split ring resonators milled from a thin layer of plasmonic material, such as gold. Such a layer will produce sharp resonance peaks in transmission and reflection in the near-IR, the spectral positions of which are sensitive to the local dielectric environment.

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Identifiers

ORCID for B. Mills: orcid.org/0000-0002-1784-1012

ORCID for D. Hewak: orcid.org/0000-0002-2093-5773

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

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