DIRECTIONAL COUPLER TYPE OPTICAL FUNCTIONAL ELEMENT AND ITS DRIVING METHOD

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 providing a coupling part C0 where two optical waveguides A and B which are loaded with propagation constant control means F1-F4 and equal in propagation constant are arranged in parallel, optically connecting the incidence ends A1 and B1 of the two optical waveguides A and B to curved or straight optical waveguides D1 and D2 to form an incidence-side lead part C1, and also optically connecting the projection ends A2 and B2 of said two optical waveguides A and B to curved or straight optical waveguides D3 and D4 to form a projection-side lead part C2; and mode coupling suppressing means F5-F8 are arranged on the respective optical waveguides D1-D4 of the incidence-side lead part C1 and projection-side lead part C2.