High power 3–12 μm infrared lasers: recent improvements and future trends

In this paper, we discuss the progress of quantum cascade lasers (QCLs) grown by gas-source molecular beam epitaxy. Room temperature QCL operation has been reported for lasers emitting between 5–View the MathML source, with 9–View the MathML source lasers operating up to View the MathML source. Laser technology for the 3–View the MathML source range takes advantage of a strain-balanced active layer design. We also demonstrate record room temperature peak output powers at 9 and View the MathML source (2.5 and View the MathML source, respectively) as well as record low View the MathML source threshold current densities View the MathML source for some laser designs. Preliminary distributed feedback (DFB) results are also presented and exhibit single mode operation for View the MathML source lasers at room temperature.