A semiconductor optical device includes a silicon substrate and a Group III-V semiconductor gain layer. The Group III-V semiconductor gain layer is formed on the silicon substrate. The silicon substrate or the Group III-V semiconductor gain layer has a dispersion Bragg grating formed therein. In a method of manufacturing a semiconductor optical device, a Group III-V semiconductor gain layer is formed on a silicon substrate. A dispersion Bragg grating is formed on the silicon substrate or the Group III-V semiconductor gain layer.