The present invention is to provide a semiconductor laser with a feedback
grating comprised of InP and AlGaInAs without InAsP put therebetween, and
to provide a method for manufacturing the DFB-LD having such grating. The
LD includes an n-type InP substrate, an AlInAsP intermediate layer, an
AlGaInAs lower SCH layer, an active layer, and a p-type layer for upper
cladding in this order from the InP substrate. The InP substrate, the
AlInAsP intermediate layer, and the AlGaInAs lower SCH layer constitute
the feedback grating. The AlInAsP intermediate layer lowers a series
resistance along these semiconductor stacks.