GaAs/GaAlAs heterostruture rib waveguide coupler with "stepped Δβ" Schottky electrodes has been investigated by using ion-etching and liftoff mask techniques, and optimization design of device structure and lowering epitaxy layer carrier concentration. Total losses of 10 dB and extinction ratio of 26.8 dB are obtained for single-mode operation at 1.3 μm.