Ultracompact programmable silicon photonics using layers of low-loss phase change material Sb2Se3 of increasing thickness

Abstract

High-performance programmable silicon photonic circuits are considered to be a critical part of next generation architectures for optical processing, photonic quantum circuits and neural networks. Low-loss optical phase change materials (PCMs) offer a promising route towards non-volatile free-form control of light. Here, we exploit direct-write digital patterning of waveguides using layers of the PCM Sb2Se3 with a thickness of up to 100 nm, demonstrating the ability to strongly increase the effect per pixel compared to previous implementations where much thinner PCM layers were used. We exploit the excellent refractive index matching between Sb2Se3 and silicon to achieve a low-loss hybrid platform for programmable photonics. A five-fold reduction in modulation length of a Mach-Zehnder interferometer is achieved compared to previous work using thin-film Sb2Se3 devices, decreased to 5 μm in this work. Application of the thicker PCM layers in direct-write digital programming of a multimode interferometer (MMI) shows a three-fold reduction of the number of programmed pixels to below 10 pixels per device. The demonstrated scaling of performance with PCM layer thickness is important for establishing the optimum working range for hybrid silicon-PCM devices and holds promise for achieving ultracompact programmable photonic circuits.

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Identifiers

ORCID for Idris A. Ajia: orcid.org/0000-0003-3156-4426

ORCID for Daniel Lawson: orcid.org/0000-0002-9499-1954

ORCID for Ioannis Zeimpekis: orcid.org/0000-0002-7455-1599

ORCID for Otto L. Muskens: orcid.org/0000-0003-0693-5504

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