| 摘要 |
PURPOSE:To prevent free carrier absorption of electrons and holes in a P<+> semiconductor layer, and an N<+> semiconductor layer which periodically sandwich a multiquantum well layer turning to an optical waveguide, and reduce light loss in the multiquantum well layer turning to the optical waveguide. CONSTITUTION:In a semiconductor optical waveguide having an optical waveguide layer 4 composed of intrinsic semiconductor constituted of multiquantum wells, and clad layers 2, 6 which sandwich the optical waveguide layer 4 and are composed of intrinsic semiconductor whose refractive index is smaller than that of the layer 4, a first conductivity type semiconductor layer 3 and a second conductivity type semiconductor layer 5 are arranged so as to periodically sandwich the optical waveguide layer,4. The impurity concentations and the thicknesses of the firft and the second conductivity type semiconductor layers 3, 5 are set in the manner in which electrons and holes in the first and the second conductivity type semiconductor layers 3, 5 are exhausted by a built-in voltage generated between the first and the second conductivity type semiconductor layeres 3, 5. |
