Reliability of 1.3-μm InGaAsP/InP laser diodes

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 I_th, high characteristic temperature T_o, and high maximum temperature for CW operation, T^CW_max. Accelerated long-term life test data predict an MTTF of ∼10⁷ h at room temperature for state-of-the-art optimized lasers with T_o ∼ 80 K, T^CW_max∼ 100°C, I_th ∼ 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.