Correlation of mid-infrared quantum-cascade laser performance with laser design parameters

Several different quantum-cascade (QC) laser designs spanning the wavelength range between similar to 3.8 and similar to 4.8 microns were grown, and devices were fabricated and tested. The active regions of these designs consist of strained layers of (In, Ga)As and (In, Al)As. For several of these designs, we varied design parameters including injector doping, section-coupling strength, and the number of QC laser periods. Lasers were tested near room temperature under both quasi-cw and low-duty-cycle conditions. Device performance is compared with theoretical expectations, and conclusions are reached on the relative merit of various design modifications.