The GaAlAs system has been often used in the monolithically integrated optics devices. This paper describes the monolithic integration of a double heterostructure GaAlAs embedded stripe laser, a GaAsP strip-waveguide and a GaAsP strip-waveguide modulator. It is seen that the maximum modulation occurs at a wavelength shorter than the peak wavelength of emission spectrum as a result of the Franz-Keldysh effect.