Feature issue introduction: mid-IR photonic materials

The mid-infrared (mid-IR, 2.5 to 10 mu m wavelengths) is a strategically important spectral band for an array of applications such as thermal imaging, chem/bio sensing, spectroscopy, infrared countermeasures, and free space communications. Mid-IR photonics have emerged as an active area of investigation in recent years, largely spurred by the rapid progress of cascade laser sources, uncooled detectors, and specialty mid-IR optical fibers. The 26 papers of this feature issue focus on the leading enabling material technologies for mid-IR photonics, and encompass recent advances in both active (lasers and detectors) and passive (fibers and waveguides) components. Linear and nonlinear photon-matter interactions in the mid-IR are also covered.