In this study, we demonstrate a highly strained 1.2 µm GaInAs/GaAs quantum well laser which may be used in high-speed local area networks. Edge emitting lasers with either a GaInP or AlGaAs cladding layer have been fabricated. We have achieved a threshold current density as low as 170 A/cm2 for GaInP-cladding-layer lasers and a high characteristic temperature T0 as high as 211 K from 30°C to 120°C for AlGaAs-cladding-layer lasers. The material gain coefficient g0 was estimated to be 1550 cm-1 which is comparable to that of 0.98 µm GaInAs lasers. A preliminary lifetime test under heatsink-free CW condition was carried out, which shows no notable degradation after 300 h. We also demonstrated an AlAs oxide confinement laser in a 1.2 µm wavelength band.