GaAs/AlGaAs microresonator quantum cascade lasers

We report on the realization of electrically pumped GaAs/AlGaAs microcylinder lasers emitting at View the MathML source. The design and fabrication process of the special resonator shapes (circular- and stadium-like cross section) are presented. The active material is a 30 period sequence of injectors/active regions made of GaAs/AlGaAs quantum wells. Far-field characteristics of these special resonators are compared and the dependence of directionality of the emission on the deformation is investigated. The bow–tie mode can be resolved in the far-field pattern. A transition from the bow–tie to another mode with highly directional emission along the short axis of the resonators is shown for the first time. Single-mode emission is detected for View the MathML source diameter circular microlasers with a side mode suppression exceeding 20 dB. The maximum working temperature of the microcylinder lasers is 165 K.