Résumé
High performance mid-infrared (2–5 μm) laser diodes are needed for applications such as high resolution and high sensitivity chemical gas analysis and atmospheric pollution monitoring. The goal is to obtain continuous wave laser emission at room temperature, with output power > 1 mW. Different technologies are under investigation to reach this objective. The GaInAsSb/AlGaAsSb strained multi-quantum-well laser showed striking results in CW operation at and above room temperature and appears as a well established technology for laser emission in the 2.0–2.7 μm wavelength range. Beyond 2.7 μm, the IV–VI lasers based on the PbSe/PbSrSe system, type-II “W” quantum well lasers based on the InAs/GaInSb system, and type-II interband and intersubband III–V cascade lasers, are competitive technologies. They could all operate at room temperature or near room temperature, but only in the pulsed regime. This paper presents an overview of the state of the art of these different mid-infrared systems emitting in the 2–5 μm wavelength range. Two heterojunction laser technologies are detailed: the 2–3 μm GaInAsSb multi-quantum-well laser, and the 3–5 μm type-II and type-II “W” laser diodes.