This letter describes 1.48 &mgr;m multiple quantum well (MQW) lasers with strained GaInAsP quaternary wells entirely grown by metalorgainic vapor phase epitaxy. The GaInAsP quaternary layers with 1.5% biaxially compressed strain showed an excellent crystal quality and an abrupt interface within half‐monolayer fluctuations which was verified with photoluminescence spectroscopy. The maximum continuous wave output power of 140 mW was obtained at 20 °C with 1500‐&mgr;m‐long lasers whose facets were coated by anti‐ and high‐reflection films. The small internal loss of 12 cm−1and a high internal efficiency of 70% were obtained.