SEMICONDUCTOR PUMP LASER TECHNOLOGY

Recent progress in high-power semiconductor lasers for erbium-doped fiber amplifiers is described: 1.48 mum InGaAsP/InP lasers and 0.98-mum InGaAs/GaAs lasers. The experimental output powers have reached over 200 mW (the maximum power was 325 mW) for 1.48 mum lasers, whereas simulation results indicate that an extremely high power of over 400 mW could be obtained by optimizing parameters in strained layer (SL) multiple quantum well (MQW) lasers. Stable operations over a few thousand hours under a high power of the 100-mW level are demonstrated for different types of lasers: liquid phase epitaxy grown lasers, MQW lasers, and SL-MQW lasers grown by all-metal organic vapor-phase epitaxy (MOVPE). For 0.98 mum lasers, improvement in the fiber coupling efficiencies and long-term reliabilities are described. A coupled power into a single-mode fiber has been improved up to over 100 mW, with high coupling efficiencies of approximately 40%. Although reliabilities seem to be one of the drawbacks compared with 1.48-mum lasers, and there have been few reports on the reliability, stable operation over 10 000 h at 50-degrees-C-30 mW has been reported.