A study of material and optical characteristics of InGaAsPAnGaP lasers grown on GaAs (100) substrate, Operating at λ = 0.8μm was carried out. The main features of InGaAsPAnGaP lasers over the conventional AlGaAs/aCAs; ones were not only stable epitaxial layer growth due to the aluminum-free material, but also strong resistance to the degradation. The other benefits of InGaAsP/inGaP laser over AlGaAs/GaAs one was the quantum-well structure growth by a simple version of liquid-phase epitaxy (LPE), which might be irnispensable to the high power operation of a semiconductor laser. The separate confinement heterostructure single quantum weil(SCH-SQW) InGaAsP/nGaP lasers were fabricated for the material charaterization of quaternary systen. The local temperature rise at the mirror facet of a InGaAsP/InGaP laser, which is the barometer of a reliable operation, was less than 30°C under even above 500 mW CW operation. We presumably attribute this low local temperatur rise of the quaternary system to the fact that it has thenodynamically stable minor facet. The surface analysis of InGaAsP layer by ESCA showed that the formation of indium oxide would prevent the elemental segragation constituting dangling orbital, which is common to A1GaAs material systems.