Mid-Infrared Vertical Cavity Surface Emitting Cascade Lasers

In this program, we propose to develop vertical cavity surface emitting lasers (VCSELs)based on cascaded type-II InAs/Ga(In)Sb/AlSb quantum wells, which will operate in the3-7 microns mid-IR wavelength region in quasi-CW mode with output power exceeding1 mW. The type-II interband cascade VCSELs retain the advantages of cascade injectionand emission wavelength tailoring, while circumventing the phonon scattering lossesand polarization selection restrictions that are present in intersubband lasers.These features make them excellent candidates for compact, reliable, high-power,mid-infrared light sources for a wide range of commercial and military applications,such as chemical sensing, communications, land-mine detection, and industrial processcontrol. The recent demonstration of interband cascade lasers with record-high powerefficiencies (>18% in pulsed mode and >14% in cw mode at 80 K) clearly shows theirpotential to fulfill the necessary requirements for practical mid-IR applications.The phase I effort will be directed towards the design, MBE growth, characterizationand optimization of type-II InAs/GaInSb/AlSb interband cascade VCSELs to demonstratetheir feasibility for chemical sensing applications. High performance mid-IR VCSELswill be developed in Phase II.If successful, the proposed effort will lead to the first mid-IR cascade VCSEL thatcan operate under cw conditions at ambient temperatures. This would enable severalcommercially viable products in several fields including the broad field of chemicalsensing. One example is provided by the need to detect, at the ppb level,formaldehyde (and related compounds) for medical diagnosis purposes. In thisinstance (and in other cases), a single mode cw laser source operating in themid-IR is essential. This effort's success will also provide laser sources neededto meet the needs of many commercial and defense applications.