Recent progress in semiconductor lasers — cw GaAs lasers are now ready for new applications

Semiconductor lasers, first demonstrated in 1962, have spent a long time in development without finding many applications. (GaAl)As double heterostructure diode lasers with stripe structure have distinctive characteristics for cw operation with a pure mode, in addition to their compactness and ease of operation. Quick degradation of these lasers has been investigated and it was found that the degradation was caused by local crystalline defects produced by internal stresses and local weakness. Improvements based on the study have provided reliable lasers with an operating life of over several thousand hours. These new generation lasers will be useful for optical communications and other optical systems.