PURPOSE: To form an optical waveguide with less optical absorption loss using super lattice structure by doping p-type or n-type impurity in such a degree as about 1×1017cm-3 to a part of high purity super lattice which indicates exciton absorption in the neighborhood of band end at a room temperature.

CONSTITUTION: After causing the undoped super lattice layer (GaAs, Al0.5Ga0.5 As, respectively 50) sandwiched by the undoped clad layers (Al0.4Ga0.6As)2, 4 to grow by the MBE method or MOCVD method on a GaAs substrate, the Be ion is doped only by 5×1016cm-3 in both sides of optical waveguide portion to obtain an optical waveguide. A semiconductor laser is formed by sequentially forming, by the epitaxial growth method, an n-clad Al0.35Ga0.65As layer 2, an undoped active layer 3 corresponding to oscillation wavelength of 0.82nm, a p-clad layer Al0.35Ga0.65As41, a super lattice undoped clad layer 42(GaAs, Al0.5 Ga0.5As), a p-clad Al0.35Ga0.65As43 on an n+GaAs substrate and thereafter the Be ion is doped up to 3×1017cm-3 in both sides of the oscillation region.