Long-Term Reliable, High-Power Midwave-Infrared Quantum Cascade Lasers

Intraband, LLC has invented and demonstrated quantum-cascade-laser (QCL) structures that both suppress carrier leakage and have efficient carrier extraction, so-called step-taper active-region (STA) QCLs. As a result, record-high internal efficiencies have been obtained, which are 30-40 % higher than conventional QCLs. Consequently, these midwave infrared (MWIR) semiconductor lasers have potential for much higher wallplug-efficiency values than conventional QCLs and much less heating under quasi-CW or CW operation. The STA design also reduces performance sensitivity to device temperature rise, which lessens the thermal management burden on systems using these lasers in real-world situations. In this program Intraband will engineer these QCLs for reliability. The effort will include optimizing the QCL chips and die bonding methods for reliable high-power operation. The primary goals of the program are to: (a) study QCL failure modes during watt-range quasi-CW and/or CW operation and determine a model of the lifetest acceleration factors; (b) Carry out lifetests with the goal of achieving stable operation of QCLs, nominally emitting at 4.6 microns, for at least 1000 hours at 1 W average-power. These results can then be applied to more advanced designs, like QCL phase-locked arrays and grating coupled surface emitters, which are a proven technologies for power scaling.