Analysis of blue/green/red coherent light radiated by surface‐emitting nonlinear generators is presented. It is shown that there are possibilities of obtaining efficient mW visible light out of these devices. Several problems in the calculation of the efficiency of these structures are discussed. These include the incorporation of the second‐harmonic reflections at the layer boundaries, the field and power continuity requirements, relation of device performances on different substrate orientations due to symmetry of the III‐V crystals, and an analysis of active surface‐emitting second‐harmonic generators.