Optical waveguide device and coherent light source and optical apparatus using the same

An optical waveguide device for converting fundamental light propagating in an optical waveguide to harmonic light propagating in the optical waveguide, comprising:

• a substrate provided with the optical waveguide, the optical waveguide having a periodic polarization inversion structure;
• and
• an entrance end face and an exit end face formed on end portions of the optical waveguide, wherein
• the optical waveguide comprises a straight waveguide that extends front the entrance end face in a direction substantially perpendicular to the entrance end face and at least one inclined waveguide that is formed between the entrance end face and the exit end face,
• the entrance end face is substantially parallel to the exit end face,
• an angle θ between the exit end face and a direction of an optical axis of the optical waveguide at the exit end face is not 90°,
• the fundamental light and the harmonic light exit from the exit end face, and
• radiation loss in the in inclined waveguide differs between the fundamental light and the harmonic light.