Ultracompact High‐Extinction‐Ratio Nonvolatile On‐Chip Switches Based on Structured Phase Change Materials

Abstract Adopting phase change material (PCM) in constructing nonvolatile on‐chip photonic switches has received intensive attention recently. Usually, a large‐area thin PCM film is directly used to construct a switch. Here, subwavelength structured PCM supporting localized resonance are adopted to efficiently improve the switching performance in a moderate bandwidth to obtain an optimal switch of higher switching contrast, smaller footprint, lower energy consumption, and better structure stability. Such a switch consisting of three cascaded Ge 2 Sb 2 Te nanodisks with a total volume of only 0.229 µm 35 nm on top of a single mode strip silicon waveguide is demonstrated. In the experimental verification, a high extinction ratio up to 27 dB is supported by the fabricated device as a high performance switch. The proposed design methodology will find its great potential in various large‐scale integration in optical interconnection and optical computing with new architectures or applications.