Mode switching and beam steering in photonic crystal heterostructures implemented with vertical-cavity surface-emitting lasers

The authors demonstrate electrically controlled mode switching and beam steering in separate-contact photonic crystal heterostructures implemented with two-dimensional arrays of coupled vertical-cavity surface-emitting lasers. Two weakly coupled, lasing photonic crystal domains are switched in and out of mutual coherence by controlling the injected currents. Switching of the transverse lasing mode is accompanied by corresponding variations in the far-field pattern and the emission wavelength. Proper adjustment of the driving currents also allows steering of the beam of the ensemble of coupled lasers.