The double‐heterostructure optoelectronic switch is demonstrated as a three‐terminal laser. The basic laser structure employs a graded index single quantum well (GRIN SQW) and implements the third‐terminal injector as a self‐aligned implant to the inversion channel. The implant simultaneously serves as the optical confining layer. Threshold currents of 500 A/cm2are obtained and complete control of the switching characteristic is obtained with an input current density of 0.8 A/cm2.