| 摘要 |
PURPOSE:To obtain a high extinction ratio in both a cross state and a through state. CONSTITUTION:The two-input, two-output directional coupler has a coupling part C0 of length L where two equal-width optical waveguides A and B made of a material with electrooptic effect are arranged in parallel. The coupling part C0 is constituted by optically connecting a front-stage part coupling part C3 of length p1XL which has a control means K2 for the state of coupling between the light guides, a front-stage coupling part C4 of length (1-p1-p2-p3)XL/2, a center coupling part C5 of length p2XL which has a similar control means K3, a rear-stage coupling part C6 and a rear-stage coupling part C7 of length p3XL which has a similar control means K4 from incidence terminals A1 and B1 in this order, where p1, p2, and p3 are decimal numbers or zero satisfying p1+p2+p3< l (p1not equal to 0). The coupling parts C1 and C2 have similar control means K1 and K5. |
