摘要： Interband cascade lasers (ICLs) combine the concept of quantum cascade lasers (QCLs) and conventional photodiodes, because they rely on the voltage-efficient in-series connection of multiple active regions as in QCLs as well as the long upper-level recombination lifetimes of photodiodes. The distinctive low power consumption of ICLs makes them especially attractive for mobile applications in the mid-infrared, such as process control, medical applications and spectroscopy. As a first proof of principle we present ICLs fabricated into ring-shaped cavities. A second order distributed feedback (DFB) grating is used for the light outcoupling of our ring ICLs, in vertical direction through the GaSb substrate. The first demonstrated devices with a waveguide width of 10 μm and 400 μm outer diameter show light emission at a wavelength of ~3.7 μm. A pulsed threshold current density <1 kA/cm2 is measured at 20°C. We are currently working on the second generation of such ring ICLs with smaller waveguides for better suppression of higher order lateral modes and larger outer diameter (e.g. 800 μm) for increased optical output power. The newly developed devices are used in a project for trace gas sensing via the principle of photothermal interferometry.