Miniature Quantum Cascade Surface Emitting Ring Lasers

Mid-infrared laser sources operating with low power dissipation on small device footprints are essential for compact and portable spectroscopic applications [1]. Quantum Cascade Lasers (QCLs) with tunable emission wavelengths in the molecular fingerprint region [2] offer a platform for developing such sources. In particular, QCL active regions embedded in ring-shaped cavities are promising candidates. The ring geometry supports low optical losses due to the formation of whispering gallery modes (WGMs) in the cavity, providing a route toward device miniaturization and reduced power consumption [3].