Power integrity of 980 nm pump lasers at 200 mW and above

More than 50 million device hours have been accumulated to date in field operation of Er/sup 3+/-doped fiber amplifiers (EDFAs) using our single-mode 980-nm semiconductor lasers as pump sources. The reliability of the E2-type pump laser has been reported earlier, and fulfills the requirements posed by terrestrial telecommunications applications, both from wear-out and from sudden-failure rate considerations. Failure analysis results show that most of the device failures are caused by catastrophic rear-mirror damage. This is likely due to the high absorption of the a-Si In the multilayer Al/sub 2/O/sub 3//a-Si stack. To prevent this type of failure mechanism, a rear-mirror stack has been developed in which the absorption has been strongly reduced. In order to test the effect of the reduced back-mirror absorption and the feasibility of operation at 200 mW a large number of E2-type lasers have been subjected to high-current and high-temperature stress tests. The devices used in the experimental work are standard 980 nm E2 lasers, i.e. 750-/spl mu/m long, MBE-grown single-quantum-well AlGaAs/lnGaAs lasers.