High quality single (SQW) and multiple (MQW) quantum well InGaAs/InP lasers have been realized for the first time utilizing a newly developed interlayer growth technique. The technique utilizes separate confinement SQW and MQW lasers grown by atmospheric pressure metalorganic vapor phase epitaxy (MOVPE) having 10–20 nm InGaAs well(s) cladded by 50‐nm‐thick InGaAsP (&lgr;g=1.46 &mgr;m) waveguide layers. Carrier confinement and interfacial layer perfection are improved by growth of a few monolayers (∼1 nm) of InP at the QW‐barrier interface and by using a novel flushing technique between growth of layers of different compositions. Both SQW and MQW lasers exhibit threshold current density of ∼2 kA/cm2. Buried‐heterostructure lasers grown entirely by MOVPE in a two‐growth step show threshold current of 18–40 mA and quantum efficiency as high as 21% facet with good linearity up to 15 mW.