LOW-THRESHOLD TENSILE-STRAINED INGAAS-INGAASP QUANTUM-WELL LASERS WITH SINGLE-STEP SEPARATE-CONFINEMENT HETEROSTRUCTURES

We studied tensile-strained InGaAs-InGaAsP quantum-well lasers with single-step separate-confinement heterostructures (SCH). We obtained threshold currents below 2 mA at 20-degrees-C and below 10 mA at 100-degrees-C with indium mole fractions of 0.3 and 0.35 in the active layers. We found that the poorer carrier confinement of the longer wavelength SCH layer lowered the characteristic temperature at high temperatures. A laser with two In0.35Ga0.65As wells and a 1.1 mum composition InGaAsP SCH layer produced a 1.6 mA CW threshold current at 20-degrees-C and lasing at 120-degrees-C. Using this laser, we achieved very short lasing delays under zero-bias current over a wide temperature range and 2 Gbit/s modulation under zero-bias current at 70-degrees-C.