Integrated photonic materials for the mid‐infrared

While silicon photonic integrated circuits for the near-infrared (IR) telecommunication band have attracted great research interest in the past decade, recent advances offer opportunities to extend the operational wavelength to the mid-IR (2.5-20 mu m) for free space communications, sensing, environmental monitoring and much more. In this study, we will comprehensively review the current status of materials available for mid-IR waveguides and waveguide integrated photodetectors, with a few application oriented examples to illustrate the technological importance and significant growth opportunity for integrated photonics in the mid-IR regime. However, this wavelength regime also presents new material design and fabrication challenges. Therefore, we will discuss the critical issues prior to commercialization and will briefly summarize the outlook on future research topics along with opportunities.