A distributed feedback laser device inhibiting beam coupling coefficient variation
resulting from fabrication dispersion and improving fabrication yield. The distributed
feedback laser device includes cladding layers provided on an InP substrate and
located on both sides of an active layer and a diffraction grating having grating
bars, different in refractive index from the cladding layers, in either cladding
layer and extending in a direction perpendicular to a light emission direction
at a prescribed pitch in the emission direction, as well as at least one light
distribution control layer, located in the cladding layer, spaced from the diffraction
grating and having the same composition as the diffraction grating.
