PURPOSE: To perform focusing and tracking at high speeds, by providing a refractive index adjusting area at a part of an optical waveguide.

CONSTITUTION: A strip-shaped refractive index adjusting area 13 is provided at the midway of an optical waveguide 9a in an optical waveguide layer 9. When the refractive index changing quantity Δn of the refractive index adjusting area 13 is zero, the laser light emitted from a semiconductor laser 11 is condensed to a light condensing spot 12 through the optical waveguide 9a. When the changing quantity Δn becomes >0, the laser light is bent at the area 13 and condensed to another light condensing spot 16 through another optical waveguide 9b. When the strip-shaped refractive index adjusting area 13 which is provided almost vertically to the laser light is controlled in such way, a focusing function can be accomplished.