PURPOSE: To omit the regulation of an optical coupling of a light source to an optical guide thereby to enhance the mass productivity of an optical integrated circuit and to reduce the cost by providing a buffer layer having a nonreflecting film having good optical alignment with the guide on the end face of a semiconductor laser resonator for mechanically aligning with the guide on a semiconductor substrate.
CONSTITUTION: A semiconductor laser 10 having an active layer 17, and clad layers 20 and 21 is formed on a substrate 9. The end face of the laser 10 in one side direction is etched to form an optical guide, and a step is formed. In case of an n-type substrate, upper and lower electrodes 11 and 12 are formed, as shown, while in case of a semi-insulating substrate, n-type electrodes are formed laterally in a planar shape. Then, a nonreflecting film 13 is formed to optically couple an optical guide 16 to the laser 10 in high efficiency. A buffer layer 14 is formed on the substrate 9. Then, a buffer layer 15 for the guide is formed on the buffer layer. Optical guide layer 16 is formed on the layer 15 at 400°C or lower.