Fabrication and performance characteristics of InGaAsP ridge-guide distributed-feedback multiquantum-well lasers

The fabrication and performance characteristics of InGaAsP ridge-guide distributed-feedback lasers with multiquantum-well active layers are reported. The lasers are 320 ¿m long and have four active wells (¿300 Å thick). The lasers have threshold current ¿100 mA at 30°C, external differential quantum efficiency ¿0.1 mW/mA/facet at 30°C and To¿ 60 K and can be operated in the same DFB mode up to 70°C. The measured frequency chirp is about a factor of 3 smaller than that for conventional double-heterostructure lasers. The smaller chirp should allow larger repeater spacing for high-bit-rate long-distance fibre transmission systems applications.