Long term reliability study and life time model of quantum cascade lasers

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

High-Power Mid-Infrared (λ∼3-6 μm) Quantum Cascade Lasers

“…Interestingly, some devices exhibit a slight improvement initially with aging and stabilize after an initial burn-in, as shown in Fig. 11 (b), which has also been reported previously [53]. The mechanism responsible for such behavior needs further study.…”

“…While ΔTact = 54 K for the TA-RE QCL at the wp,max point (i.e., 21 % at 4.25 W output power), for the case T0 = 244 K, T1 = 750 K, Rth = 1.6 K/W,  i = 90 % ΔTact is only 16.6 K at 4.25 W output power. Such a relatively low value is close to the ~ 15 K value for the low-CW-power (~ 0.2 W) 4.6 μm-emitting QCLs that have demonstrated long-term reliability [53]. Therefore, we conclude that optimized QCLs hold the potential to have long-term reliability at multi-watt CW output power levels.…”

“…QCLs are expected to have different degradation and failure modes than diode lasers, because nonradiative recombination and subsequent optical absorption at the facets is not an issue. QCL lifetests have been reported which were carried out at relatively low output powers (~200 mW) and revealed activation energies as high as 1.2 eV, with the primary failure mechanism being oxidation of the front uncoated facet [53]. Higher output power (~ 1W CW), constant-power, lifetest studies of QCLs emitting at λ ~ 5.0 μm have shown that stable operation can be achieved over 2500 hours at room temperature, as shown in Fig.…”

“…The estimated activeregion temperature is ~70 o C, based on correlating thermal simulations with thermal-reflectance measurements on BH lasers [63]. In [62], to mitigate the failure mechanism previously observed at lower output powers in [53] as well as to improve device output, both facets have coatings: a high-reflectivity (HR) back-facet coating and a 14% low-reflectivity (LR) front-facet coating. The devices were mounted episide-down on copper with indium and tested under constant-power operation in a controlled environment.…”

Heat Dissipation Schemes in AlInAs/InGaAs/InP Quantum Cascade Lasers Monitored by CCD Thermoreflectance

“…Image shows a blister on the facets of the device, formed during the catastrophic damage of laser in the vicinity of front facet. Recently, an increased number of degradation observations is reported in the literature [8][9][10]. The problem is undertaken by leading research centers, mostly by theoretical analyses with very few reports concerning experimental works towards the explanation of the observed degradation modes.…”