Mid-IR supercontinuum generation dynamically controlled by Sb2S3 phase-change material

Photonic circuits operating in the mid-infrared (mid-IR) range can greatly benefit from a bright, broadband light source such as a supercontinuum (SC) generated in integrated waveguides. In this work, we present an effective approach to fabricate a SC source with tunable properties tailored to specific applications. This is achieved through the hybrid integration of phase-change materials (PCMs), such as Sb₂S₃, into a SiGe-on-Si photonic platform. To address the high propagation losses associated with the crystalline phase of the PCM, we designed a hybrid waveguide structure that minimizes light interaction with Sb₂S₃. The use of a Si or Ge top cladding enables a significant dispersion shift of the guided mode for different Sb2S3 states. We fabricate the waveguides and conducte SC generation experiments by pumping them at the wavelength of 3.9 μm with 200 fs long pulses. Our results show that Ge-clad waveguides exhibit a pronounced modification of their nonlinear response upon Sb₂S₃ crystallization, highlighting the potential of this hybrid approach for mid-IR photonic applications.