Intra-pulse modal instability and beam steering in Quantum Cascade laser

Time-resolved far-field measurements of Quantum Cascade lasers show intra-pulse beam steering on the nanosecond scale. Spatially-dependent spectra at different pulse times show evidence of frequency locking between transverse modes when the beam steering happens. The light pulse instability has been found to reduce the device received output power by 20% in some cases. A proposal on how to reduce the instability by transverse mode control is presented.