Monolithic integration is described of an embedded stripe DH laser with an embedded strip waveguide of vapor‐phase‐grown GaAsP. The waveguide is composed of high‐resistivity GaAs0.9P0.1and surrounded by GaAs0.85P0.15, whose refractive index is slightly lower, to provide the optical confinement in both directions parallel and perpendicular to the guide plane. The intensity modulation of the output light was efficiently achieved by applying an electric field to the waveguide.