Electrically pumped semiconductor lasers are among the most important sources, owing to their high efficiency, compactness, and solid-state stability. For mid-infrared and terahertz radiation, quantum cascade lasers (QCLs) are the most important light sources operating via electrical pumping. To demonstrate single-mode laser emission, artificially designed distributed-feedback (DFB) gratings can be patterned on top of a ridge laser.
Click here for original story, Topological bulk BICs enable compact, single-mode and beam-engineered QCLs
Source: Phys.org