Phase-change material enabled silicon phase shifter actuated by a highly durable graphene microheater

We demonstrate a high-efficiency silicon optical phase shifter based on a silicon-Sb2Se3 hybrid integrated waveguide. The optical field has large confinement in the Sb2Se3 material, leading to high optical wave modulation efficiency upon phase change of Sb2Se3. The phase change is initiated by electro-thermal heating generated by a highly durable graphene microheater positioned between the Sb2Se3 strip and the silicon slab of the hybrid waveguide. To effectively couple the phase shifter with single-mode silicon waveguides, we design a two-layer taper structure as a mode spot size converter. Utilizing this phase shifter, we implemented a Mach–Zehnder interferometer structure to function as an optical switch. The number of effective switching events exceeds 30,000, and 66 non-volatile switching levels are obtained. Our work provides an effective solution for introducing highly durable graphene microheaters on silicon-based phase-change platforms.