| 摘要 |
PURPOSE:To suppress the spreading angle of an exit beam to a lower angle by parting the light exit end face of an optical waveguide from a substrate end face, then forming the part of the optical waveguide adjacent to the light exit end face so as to have the refractive index lower than the refractive index of the other part of the optical waveguide. CONSTITUTION:The light exit end face 11b of the optical waveguide 11 formed on the transparent substrate 16 is positioned apart from the end face 16a of the substrate 16 toward the inner side and the part adjacent to this light exit end face 11b is formed lower in the refractive index than the other part 11 of the optical waveguide. The laser beam 13 emitted from a semiconductor laser 18 into the optical waveguide 11 progresses in the optical waveguide 11, is emitted once from the light exit end face 11b to the part of the substrate 16 and is emitted from the substrate end face 16a to the outside of the substrate 16. Since the part adjacent to the light exit end face 11b of the optical waveguide 11 is formed lower in the refractive index than the other part of the optical waveguide, the confinement of the guided light 13 in this part is weakened and as a result, the diffraction at the time when the light beam 13B is emitted is weakened. The spreading angle phi3 is thus decreased as the spreading is suppressed. |
