Current- and Temperature-Induced Beam Steering in 7.8- m Emitting Quantum-Cascade Lasers

We report large current- and temperature-induced beam-steering effects, observed in the far-field distribution of InP-based quantum-cascade lasers emitting around 7.8-mum wavelength operated in pulsed mode. Changing the temperature within a narrow range of ~10degC around room-temperature leads to a change in the direction of the output beam, as given by the central lobe in the far-field intensity distribution, from +11deg to -13deg as measured relative to the resonator axis. This beam steering effect is linked to changes in the lateral mode distribution, as revealed by time-resolved spectroscopy of the lasing spectrum.