Mid-infrared (~2.8 μm to ~7.1 μm) interband cascade lasers
20 years after their first reference interband cascade lasers (ICLs) have become a mature and competitive semiconductor laser source in the mid-infrared region. The carrier rebalancing concept that was introduced in 2011 drastically improved the performance. As a consequence the wavelength window that is accessible for ICLs operating at ambient temperatures could be extended. For GaSb based ICLs continuous wave (cw) emission at room temperature could be achieved up to a wavelength of 5.6 μm. As the need for thicker claddings at longer wavelengths makes the growth of the superlattice claddings increasingly difficult and limits the heat dissipation, a plasmon waveguide structure with highly doped InAslayers grown on InAs-substrates is typically used for ICLs emitting up to ~7 μm in pulsed mode at room temperature. With regard to the short wavelength limit of ICLs, we present cw emission of a GaSb based ICL emitting at 2.8 μm and with regard to the long wavelength limit we present room temperature pulsed operation of an InAs based plasmonic waveguide ICL up to 7.1 μm. Furthermore, we show single mode emitting ICLs with distributed feedback gratings emitting between 2.8 and 5.2 μm.