We report on a DFB laser technology for GaAs based lasers. Such a structure is normally problematic to achieve due to overgrowth on Al containing layers. Our technique is to use an InGaP/GaAs grating layer in conjunction with AlGaAs cladding layers, where the AlGaAs is never exposed to air. Due to the high refractive index contrast of InGaP/GaAs, the grating layer is ~450 nm from the active layer, which helps in minimising any deleterious effects of the re-growth process on laser performance. The initial structure was grown by MOVPE process. The epitaxial structure was designed by modelling confinement factors in a commercial refractive index mode solver.