Towards reconfigurable photonics in Ge-based platforms for nonlinear mid-infrared broadband sources (Invited Paper)

Mid-infrared (MIR 3-15 μm) photonics is a burgeoning scientific and technological field with wide potential application domains including pollution detection, environmental monitoring, security, safety, astrophysics and many more...One of the key aspects is that many important molecules have fundamental ro-vibrational absorption lines in the MIR. An appealing approach, to create power efficient, sensitive, precise, compact molecular sensing devices is to develop an on-chip MIR platform integrating a bright and broadband light source, such as an integrated supercontinuum or a Kerr micro-comb. Ge-based platform (e.g. silicon germanium) has emerged as an attractive platform for nonlinear MIR photonics. We report on our latest progress on reconfigurable Ge-based photonics for bright and broadband MIR sources. We demonstrate that Phase change materials, like Sb₂S₃, are suitable for reconfigurable supercontinuum generation. We also report Ge-based ring resonators with quality factors reaching up to one million which is highly promising for power efficient MIR microcomb generation.