Quantum Cascade Surface-Emitting Photonic-Crystal Laser

In this article we report a device that incorporates both photonic and electronic band-engineering to create a novel surface-emitting Quantum Cascade microcavity laser source. In this device a high-index contrast planar two-dimensional photonic crystal is used to form the resonator providing feedback necessary for lasing action, and to diffract light vertically up from the surface of the semiconductor chip. A top metallic contact is used to form both a conductive path for current injection as well as to provide vertical optical confinement to the active region through a bound surface plasmon state at the metal-semiconductor interface. The combination of size reduction, vertical emission, and lithographic tailorability of the emission properties enabled by the use of a high-index contrast photonic crystal resonant cavity makes possible a host of active sensing applications in the mid- and far-infrared.