High-power continuous-wave mid-infrared quantum cascade lasers based on strain-balanced heterostructures (Invited Paper)

Limiting factors for short-wavelength QCL designs are discussed, and a model is described to predict the short-wavelength limit for strain-balanced QCL structures. High performance is predicted at wavelengths as short as 3.0mm based on a conduction band offset of 0.9 eV in the GaInAs/AlInAs materials. Recent work is presented on the growth of strained materials using gas-source molecular beam epitaxy to investigate the model predictions. Advanced material characterization, including HR-STEM, high-resolution x-ray diffraction, photoluminescence, atomic force microscopy, and wafer-scale uniformity and repeatability are demonstrated for strain-balanced QCL structures. Laser testing results are presented for QCLs operating at ~4.8mm, and lastly, predictions for further performance improvement at short wavelengths are discussed.