Integrated nonlinear photonics in the longwave-infrared: A roadmap

This article presents an overview of the current status and future prospects of integrated nonlinear photonics in the long- wave infrared (LWIR) spectrum, spanning 6 to 14 mu m. This range is well-suited for applications such as chemical identification, environmental monitoring, surveillance, search and rescue, and night vision. Nevertheless, the advancement of a mature, low-loss chip-level platform for the LWIR remains in its infancy. We examine the materials growth techniques, and fabrication methods associated with integrated nonlinear photonics in the LWIR, highlighting promising platforms like chalcogenide glass, single-crystalline diamond, Ge/SiGe, and III-V compounds. Furthermore, we explore loss mechanisms, dispersion engineering, nonlinear generation of broadband supercontinuum and frequency combs, and device performance, encompassing photodetectors and modulators. Lastly, we propose a roadmap for the future development of integrated nonlinear photonics in the LWIR.