A multi-physics cellular automata model for simulating phase change photonics devices

Chalcogenide phase change materials have many fascinating characteristics, i.e. extraordinarily large optical and electrical changes and non-volatility, making them appealing for information storage and reprogrammable photonics. Designing programmable photonics devices requires an accurate model to describe the switching behavior. Here, we present a multi-physics cellular automata-based framework which combines laser-induced heating, Gillespie’s Cellular Automata approach, effective medium theory and Fresnel’s Laws to model the microstructural evolution and concomitant optical response of phase change photonics devices. From the framework, we can simulate the change in optical constants during the phase switching process as well as the transient change in crystallite distribution, reflection, and transmission. The accuracy of the multi-physics model is also verified by nanosecond-pulsed laser switching experiments and transmission electron microscopy.