The properties of gas source molecular beam epitaxy grown InGaAsP bulk layers and InGaAs/InGaAsP strain-compensated multiple quantum well (SCMQW) structures an GaAs were studied by double crystal x-ray diffraction and photoluminescence measurements. It was found that high quality of SCMQW can be obtained below a critical growth temperature. Above the temperature, an immiscible growth for the InGaAsP alloy degraded both the optical and structural qualities of the MQW structures. Based on these findings, a high performance 0.98 mu m Al-free InGaAs/InGaAsP/InGaP two-step graded index separate confinement heterostructure quantum well laser was prepared at the optimal growth temperature.