Improving transverse mode quality of broad area quantum cascade lasers

Results of novel broad area QCL waveguides fabricated at Air Force Research Laboratory are discussed. An "ultrawide" Fabry-Perot waveguide design is modified to bring the waveguide mode closer to the electrical contact and splitting said contact into a Dual Contact Strip. The mode quality in the fabricated ultrawide device is rectified to fundamental-like behavior. Overlapped angled cavity waveguides with a low tilt angle, interrupted with "notches" etched out of areas far from the internal beam path of the fundamental mode, are designed and fabricated. The beam quality of the overlapped angled cavity array demonstrates coherence between outputs.