| 摘要 |
An optical waveguide formed in an electro-optical crystal substrate includes a curved waveguide (11); and a branch portion (12) that is coupled to the curved waveguide and branches light input into the curved waveguide (11) into two optical paths, wherein the curved waveguide (11) extends between a start point having a first width (W1) and an end point having a second width (W2), the branch portion (12) being coupled to the curved waveguide (11) at said end point, and wherein a low refraction index portion (18) having an effective refraction index that is lower than that of the start point of the curved waveguide is provided the curved waveguide (11) in the proximity of said end point. |
