Tuning Photonic Crystal Cavity Resonances with Phase Change Material GeTe*

Photonic crystal slabs are a promising architecture for a variety of computational and sensor architectures including quantum computers and neuromorphic networks. Such devices consist of a 2-D membrane of cavities and waveguides with embedded quantum dots (QDs). While many advances such as demonstrations of indistinguishable single photon sources and quantum entanglement have been shown, such devices are still difficult to scale as a network. The primary limitations are from natural variations during material growth and device fabrication, which cause resonances of the QDs and cavities to span energies much larger than their linewidths. One solution is to use capping layers which can tune the underlying device, changing properties such as strain and effective index of refraction, and whose structural phase can be locally altered using laser annealing, potentially allowing for local tuning of QDs or cavities. We show results of using thin films of such a phase change material, GeTe, to tune cavity resonances independent of local QDs in such devices. This tuning is dependent on the original resonance energy of the cavity and the amount of material deposited.