Degradation mechanisms and methods for reliability improvement in 1.3-μm quaternary lasers for use in submarine fiber optic cable communications are reviewed. The reliable diode requires an optimized structure, such as a thin active layer and a narrow stripe width, to achieve a low threshold current Ith, high characteristic temperature To, and high maximum temperature for CW operation, TCWmax. Accelerated long-term life test data predict an MTTF of ∼107 h at room temperature for state-of-the-art optimized lasers with To ∼ 80 K, TCWmax∼ 100°C, Ith ∼ 20 mA, and 5-mW optical power, which barely meets the system requirement. Based on the present rate of reliability improvement, a useful life of ∼109 h is forecast by 1986.
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