For making surface‐emitting lasers such as InGaAsP/InP double‐heterostructure lasers, it is important to select and study the resonator properly. The authors have compared the relative light output power of two different structures, the plane‐parallel and the hemispherical resonators. The InGaAsP/InP double‐heterostructure was grown by liquid phase epitaxy. The different resonators on the same wafer were fabricated using chemical etching, lithography, evaporation, and other integrated circuit process techniques. Output optical power of the devices with the hemispherical resonator is a factor of 2 larger than those with the plane‐parallel resonator. This is because the hemispherical resonator structure has a smaller diffraction loss than the plane‐parallel structure.