Ultralow threshold 1.3-μm strained-QW lasers for high-speed optical interconnections

A monolithic semiconductor laser array on a p-type substrate with low threshold current and uniform characteristics, is required for parallel high-speed optical interconnection. It is indicated that the threshold current should be lower than about 3.0, 1.4 and 0.7 mA at 25°C for 200 and 500 Mbits/s and 1 Gbit/s applications, respectively, to get an error-free transmission at 85°C with a shorter turn-on delay time. This paper reviews the ultralow threshold properties of 1.3-μm strained-multi-quantum-well laser. The active width and the number of quantum wells are optimized based on theoretical model to reduce the threshold current. The drastic reduction in threshold current due to the strain-induced effect is achieved with an optimized strain value of 1.4%. Thus, this array is suitable as a light source for practical use in high-speed parallel optical data link applications.