| 摘要 |
PURPOSE:To obtain a >=30dB high extinction ratio in both of a cross state and a through state. CONSTITUTION:The two-input, 2-output directional coupler optical functional element is constituted by providing a coupling part C0 where two optical waveguides A and B which are loaded with propagation constant control means F1, F2, F3, and F4 and equal in propagation constant are arranged in parallel, optically connecting the incidence ends A1 of only one of the two optical waveguides A and B, i.e., optical waveguide A to one straight optical waveguides E1 to form an incidence-side lead part C1, and also optically connecting the projection ends A2 and B2 of the two optical waveguides A and B to curved or straight optical waveguides D3 and D4 to form a projection- side lead part C2 connected to a through port E and a cross port E4; and mode coupling suppressing means F5 and F6 are arranged on the respective optical waveguides D3 and D4 of the projection-side lead part C2. |
