Catastrophic and latent damage in GaAlAs lasers caused by electrical transients

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Abstract
A study has been made of the susceptibility of 20-μm oxide stripe GaAlAs lasers to current transients. The current amplitude (as a function of duration) required to cause increased threshold currents or degradation rates has been found. Damage caused by forward bias transients was found to occur at the facets and was probably due to high surface recombination, leading to local absorption and excessive heating. Even when the immediate damage was insufficient to cause a detectable increase in threshold current, increased degradation rates resulted. Damage during reverse bias transients resulted from local avalanche breakdown which, though usually observed at the facets, was occasionally found outside the stripe. Such damage did not always lead to increased degradation rates. The reverse bias breakdown voltage of the lasers was found to be a more sensitive indicator of transient damage than the threshold current. The results provide substantial evidence to confirm that precautions must be taken against electrostatic discharge whenever lasers are handled. In addition, all laser bias circuitry, including that in test and measurement equipment as well as in optical fiber systems, must be checked to ensure that dangerous transients cannot occur.