Beam steering in mid-infrared emitting quantum-cascade lasers

We report large beam steering effects, observed in the far-field pattern of InP-based mid-infrared quantum-cascade lasers along the slow axis. Changing the temperature by a few degrees around room temperature or varying the drive current strongly affects the lateral direction of the output beam. The position of maximum intensity in the far-field-distribution changes by more than 20°. This beam steering effect is correlated to changes in the lateral mode distribution, as revealed by time-resolved spectroscopy of the lasing spectrum.