Layer intermixing in GaAs‐AlGaAs superlattices achieved by Zn thermal diffusion has been used to fabricate buried channel optical waveguides. Linear waveguides with small, abrupt bends were made and light was seen to be transmitted through these for bend angles up to 7.5 degrees corresponding to an effective index of refraction difference of 0.9% for a 50% average Al composition of the layers bounding the superlattice. For radiation between the band gap of bulk GaAs (870 nm) and the effective band gap of a 10‐nm GaAs quantum well (840 nm), the 3‐mm‐long waveguides appeared to be semitransparent suggesting a possible use in planar, buried channel all‐semiconductor integrated optoelectronics.