Designing nonvolatile integrated photonics with low-loss optical phase change materials

The development of low-loss optical phase change materials (O-PCMs) promises to enable a plethora of nonvolatile integrated photonic applications. However, the relatively large optical constants change between different states of calls for a set of new design rationales. Here we report a non-perturbative design that enables low-loss device operation beyond the traditional figure-of-merit limit. The basic design rationale is to engineer the light propagation path through the OPCMs when it is in the low-loss amorphous state, and divert light away from the lossy crystalline state leveraging the large mode modification induced by the O-PCM phase transition. Following this approach, we demonstrate broadband photonic switches with significantly enhanced performances compared to current state-of-the-art.