A semiconductor optical device with a differential grating formed by a holography
method and a method for manufacturing the same are provided. The provided semiconductor
optical device includes an n-type InP substrate, a stack structure on the InP substrate
having a waveguide and active layers, a first grating formed under the stack structure
and on the InP substrate, and a second grating formed on the stack structure. The
provided method for manufacturing the semiconductor optical device forms a first
grating on the n-type InP substrate and under the active layer, and forms a second
grating on the active layer. The first and second gratings are formed by the holography method.
