Phase-change materials (PCMs) provide a unique combination of properties. On transformation from the amorphous to crystalline state, their optical properties change drastically. Short optical or electrical pulses can be utilized to switch between these states, making PCMs attractive for photonic applications. We review recent developments in PCMs and evaluate the potential for all-photonic memories. Towards this goal, the progress and existing challenges to realize waveguides with stepwise adjustable transmission are presented. Colour-rendering and nanopixel displays form another interesting application. Finally, nanophotonic applications based on plasmonic nanostructures are introduced. They provide reconfigurable, non-volatile functionality enabling manipulation and control of light. Requirements and perspectives to successfully implement PCMs in emerging areas of photonics are discussed.

相变材料（PCM）提供了独特的性能组合。从非晶态转变为结晶态时，它们的光学性质会急剧变化。短的光脉冲或电脉冲可用于在这些状态之间切换，从而使PCM对光子应用具有吸引力。我们回顾了PCM的最新发展，并评估了全光子存储器的潜力。朝着这个目标，提出了实现具有逐步可调传输的波导的进展和现有挑战。颜色渲染和纳米像素显示器形成了另一个有趣的应用程序。最后，介绍了基于等离激元纳米结构的纳米光子应用。它们提供可重新配置的非易失性功能，从而可以对光进行操纵和控制。