Photonic Ge-Sb-Te phase change metamaterials and their applications

The ultrafast, reversible, nonvolatile and multistimuli responsive phase change of Ge-Sb-Te (GST) alloy makes it an interesting "smart" material. The optical features of GST undergo significant variation when its state changes between amorphous and crystalline, meaning that they are useful for tuning photonic components. A GST phase change material (PCM) can be efficiently triggered by stimuli such as short optical or electrical pulses, providing versatility in high-performance photonic applications and excellent capability to control light. In this review, we study the fundamentals of GST-tuned photonics and systematically summarise the progress in this area. We then introduce current developments in both GST-metal hybrid metamaterials and GST-based dielectric metamaterials, and investigate the strategy of designing reversibly switchable GST-based photonic devices and their advantages. These devices may have a vast array of potential applications in optical memories, switches, data storage, cloaking, photodetectors, modulators, antennas etc. Finally, the prospect of implementing GST PCM in emerging fields within photonics is considered.