| 摘要 |
PURPOSE:To relieve the preparing conditions for obtaining a cross state and to obtain a high extinction ratio by changing the widths of the 1st and 2nd waveguides according to the distance in the waveguide direction of an optical switch so as to maintain the adequate difference in the equiv. refractive index between the 1st and 2nd waveguides. CONSTITUTION:The 1st and 2nd waveguides 21, 22 are formed to a substrate consisting of LiNbO3-z or the like. Electrodes 23, 24 are respectively provided on the waveguides 21, 22. The width of the wave guide 21 is successively increased according to the increase of the waveguide distance z from the start point (z=0) of the guided wave of the optical switching element which is the one end edge of the electrodes 23, 24 to increase the equiv. refractive index together with the waveguide distance. The 2nd waveguide 22 is disposed to curve with respect to the 1st waveguide 21 to change the coupling coefft. between the waveguides 21 and 22 according to the increase of the waveguide distance. |
