A semiconductor laser includes an active layer on an n-type InP substrate.
A diffraction grating and a p-type InP cladding layer are above the
active layer. The diffraction grating has at least one phase shift
portion. Facets of the distributed feedback laser each have thereon an
antireflective film having a reflectance of 3% or less. The diffraction
grating does not extend into end regions of the distributed feedback
laser, each end region extending 1 .mu.m-20 .mu.m from a respective one
of the facets toward an opposite end in a waveguide direction.