A low clad layer made of semiconductor of a first conductivity type is
formed on a semiconductor substrate. An active layer is formed on the low
clad layer. The active layer is constituted by alternately stacking a
strained well layer and a barrier layer. A partial or whole thickness of
the active layer is periodically removed along a first direction parallel
to the surface of the semiconductor substrate to form a diffraction
grating. A filler made of semiconductor is embedded in the removed region.
Strain of the strained well layer and strain of the filler have the same
sign. An upper clad layer is formed on the active layer and filler and
made of semiconductor of a second conductivity type. A semiconductor laser
device is provided which has a smaller shift of spontaneous emission or PL
even if a diffraction grating is formed in an active layer.
