In this work, we explore inverse designed reconfigurable digital metamaterial structures based on phase change material Sb₂Se₃ for efficient and compact integrated nanophotonics. An exemplary design of a 1 × 2 optical switch consisting of a 3 µm x 3 µm pixelated domain is demonstrated. We show that: (i) direct optimization of a domain containing only Si and Sb₂Se₃ pixels does not lead to a high extinction ratio between output ports in the amorphous state, which is owed to the small index contrast between Si and Sb₂Se₃ in such a state. As a result, (ii) topology optimization, e.g., the addition of air pixels, is required to provide an initial asymmetry that aids the amorphous state's response. Furthermore, (iii) the combination of low loss and high refractive index change in Sb₂Se₃, which is unique among all phase change materials in the telecommunications 1550 nm band, translates into an excellent projected performance; the optimized device structure exhibits a low insertion loss (∼1.5 dB) and high extinction ratio (>18 dB) for both phase states.

中文翻译：

---

用于超紧凑可重构纳米光子器件的相变材料 Sb2Se3 的独特前景

在这项工作中，我们探索了基于相变材料 Sb ₂ Se _{3 的}逆向设计的可重构数字超材料结构，以实现高效紧凑的集成纳米光子学。演示了由 3 µm x 3 µm 像素化域组成的 1 × 2 光开关的示例性设计。我们表明：（i）直接优化仅包含 Si 和 Sb ₂ Se ₃像素的域不会导致非晶态输出端口之间的高消光比，这是由于 Si 和 Sb ₂之间的小指数对比度硒₃在这样的状态。因此，需要 (ii) 拓扑优化，例如添加空气像素，以提供有助于非晶态响应的初始不对称性。此外，(iii) Sb ₂ Se _{3 的}低损耗和高折射率变化的结合，这在电信 1550 nm 波段的所有相变材料中是独一无二的，转化为出色的投影性能；优化后的器件结构在两个相位状态下均表现出低插入损耗 (∼1.5 dB) 和高消光比 (>18 dB)。