Epi-down and epi-up bonded high-power single-mode 980-nm lasers has been studied in terms of bonding process, thermal behavior, optical performances, and long-term laser reliability. We demonstrated that epi-down bonding can offer lower thermal resistance and improved optical performance without degrading the long-term laser reliability. An optical power of 630 mW was obtained for the first time from an epi-down bonded 980-nm pump module. Our studies have shown that epi-down bonding of single-mode 980-nm lasers can reduce junction temperature and thermal resistance by up to 30%. Experimental measurements showed over 20% in thermal rollover power improvement and over 25% reduction in wavelength shift versus current in epi-down mounted lasers compared to epi-up mounted lasers. Lifetime test over 14 000 h at 500 mA and 80 C of the epi-down bonded lasers is reported for the first time.

No abstract

No abstract

No abstract

Here, we present results of quantum cascade laser lifetime tests under various aging conditions including an accelerated life test. The total accumulated life time exceeds 1.5 million device•hours. The longest single device aging time was 46.5 thousand hours without failure in the room temperature aging test. Four failures were found in a group of 19 devices subjected to the accelerated life test with a heat-sink temperature of 60 °C and a continuous-wave current of 1 A. Failure mode analyses revealed that thermally induced oxidation of InP in the semi-insulating layer is the cause of failure. An activation energy of 1.2 eV is derived from the dependence of the failure rate on laser core temperature. The mean time to failure of the quantum cascade lasers operating at a typical condition with the current density of 5 kA/cm 2 and heat-sink temperature of 25°C is expected to be 809 thousand hours. After more than two decades of development [1-2], quantum cascade lasers (QCL) have become the most important and promising laser source in the mid/far infrared wavelength range, and they have gradually been introduced in various commercial applications, including trace gas