Abstract

Today various kinds of optical fiber transmission system have been developed and put into operation. In short-haul systems or low-bit-rate (or analog) systems, such as local area networks and subscriber systems, surface-emitting-type InGaAsP/InP LEDs (S-LEDs) are mainly used. In severe temperature conditions (from <0 to around 70°C), these S-LEDs must be highly reliable. For recently developed LEDs, gradual degradation (degradation failure) is scarcely observed even under accelerated aging, and their lifetime cannot be estimated exactly.¹ The reliability of S-LEDs has come to depend on random failure modes, and less than 100 FIT at 70°C is estimated. In other words, this indicates that the InGaAsP/InP double heterostructure (DH) is quite stable. A gradual degradation, however, is still frequently observed in lasers during long-term aging.

© 1988 Optical Society of America