2. Overview of the state of the art in mid-IR single mode laser diodes

In this section an overview of the current state of the art in compact monolithic single mode laser diodes emitting in the 2.0 μm spectral region will be outlined. Focusing on monolithic chips, external cavity laser devices are not included here. The review will start with an overview of the material systems available for the laser active region emission in the 2 μm spectral region. To date single mode semiconductor lasers have been demonstrated in both the GaSb and indium InP material systems. Both material systems have their pros and cons and an overview of the various technology implementations for achieving single wavelength mode operation in each material system is shown.
