The fabrication of GaAs-based optoelectronic components by the technique of focused ion beam (FIB) implantation mixing is reviewed. The basic mechanisms and practice of the FIB-induced mixing process of GaAs/AlGaAs multiple quantum well and superlattice structures are discussed, The use of the FIB mixing technique for the fabrication of optoelectronic devices (such as channel waveguides and distributed Bragg reflection distributed feedback lasers) by the single-step, maskless/resistless FIB implantation process is described and their characteristics are reviewed.