ACCELERATED AGING TEST OF GA1-XALX AS DH LASERS

An accelerated aging test is performed at temperatures of 70, 110, and 140 °C to estimate the activation energy. Samples are operated in the LED mode at high temperatures of 110 and 140 °C. At 70 °C samples are operated in lasing mode of optical output 0.27 mW/μm. The laser lifetime is defined to be a time at which the cw threshold current measured at a standard temperature 25 °C reaches 1.5 times the initial value. The activation energy 0.74 eV is obtained. It is shown that the degradation does not depend on the optical output power below the power level of 0.3 mW/μm and that the activation energy is indifferent to the operation mode, LED mode, or lasing mode, at a low power level. The use of the LED mode operation and the definition of the laser lifetime in terms of the characteristics at low standard temperature enable one to perform the accelerated aging test at high temperatures above 110 °C where cw operation is almost impossible. The reliability is examined at 70 °C using 50 samples and an average laser lifetime is obtained. The application of the activation energy gives the average laser lifetime at the junction temperature of 30 °C to be 3×105 h.