Abstract

With the advancement and availability of high-resolution lithography techniques, nanostructuring high-index dielectric and plasmonic media on the subwavelength scale have demonstrated high-quality factor optical resonant devices within the umbrella of metamaterials and metasurfaces [4]. Chalcogenide phase-change alloys, comprised of group 16 elements such as sulphur, selenium and tellurium, are high refractive index media in the infrared spectrum exhibiting a unique reversible, non-volatile switching between the amorphous and crystalline material phases. Transitioning between phases can be actuated through optical, electrical, or thermal stimuli; thus, making them ideal for integration with silicon photonics. However, the mitigation of high insertion losses when introducing these materials to the vicinity of the waveguide due to inherent optical losses, have resulted in devices with large footprints and poor modulation contrasts. This is a real barrier to scaling up of such systems to the number of nodes needed per chip for efficient realistic neuromorphic acceleration and processing.

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