Low current operation of GaAs/AlGaAs based quantum cascade lasers

Summary form only given. Although the threshold current density of quantum cascade lasers is continuously decreasing, the true current at threshold remains large. This is mainly imposed by the long emission wavelengths of these devices which require larger ridge sizes. Therefore a considerable reduction of the current could come from a decrease of the device dimensions. The major obstacles to this strategy are the increased scattering losses of the optical mode with the edges of the laser ridge and the higher mirror losses for shorter cavity lengths. To overcome the problem of the scattering losses we have developed a processing technology based on ion-implantation, which separates the electrical from the optical confinement.