High-power room temperature emission quantum cascade lasers at λ=9 μm

We present two different techniques for processing InP-based λ=9 μm quantum cascade lasers which improve the thermal dissipation in the device. The first process is based on hydrogen implantation creating an insulating layer to inject current selectively in one part of the active region. The second process uses a thick electroplated gold layer on the laser ridge to efficiently remove the heat produced in the active region. Each process is designed to improve heat evacuation leading to higher performances of the lasers and will be compared to a standard ridge structure from the same wafer. We give evidence that the process of proton implantation, efficient in GaAs based structures, is not directly applicable to InP based devices and we present a detailed analysis of the thermal properties of devices with an electroplated gold thick layer. With these lasers, an average power of 174 mW at a duty cycle of 40% has been measured at 10°C.