Extending VCSEL wavelength coverage to the mid-infrared

There are several important gases that are detectable with mid-infrared light, having wavelengths between 3-4 micrometers. Application-grade Vertical-cavity surface-emitting lasers (VCSELs), however, aren’t yet available for this wavelength range, but the increasing need for compact, portable and affordable gas sensors is spurring demand for energy-efficient semiconductor sources of mid-IR light. Addressing this demand, a group of researchers set out to develop a concept to extend the wavelength coverage of VCSELs into this important regime.