Optical power-handling capabilities and temporal dynamics of reconfigurable phase-change metasurfaces

Metasurfaces based on chalcogenide phase-change materials offer a highly promising route towards the realization of non-volatile reconfigurable metasurfaces. However, since their switching mechanism between amorphous and crystalline states is based on thermal stimuli, phase-change metasurfaces should be treated carefully when operating under high power laser sources, since optically induced heating could trigger unwanted state changes during their operation. In this work, therefore, we develop a thermodynamic model capable of tracking the crystallization, melting and reamorphization dynamics of phase-change optical metadevices, and so too their optical performance, when operating under (i.e., aiming to control) high power laser sources. Our model is used, by way of example, to ascertain the optical power-handling capabilties of two typical phase-change metasurface architectures, one for beam steering and one for active lensing.