A semiconductor laser, including: an n-type cladding layer that has n-type
conductivity; an active layer formed on top of the n-type cladding layer;
a p-type cladding base layer that is formed on top of the active layer and
has p-type conductivity; a current-blocking layer that is formed on
specified parts of an upper surface of the p-type cladding base layer and
substantially has n-type conductivity; and a p-type buried cladding layer
that has p-type conductivity and is formed so as to cover the
current-blocking layer and contact remaining parts of the upper surface of
the p-type cladding base layer. The current-blocking layer has at least
two regions having different concentrations (hereafter "N1" and "N2" where
N1
