| 摘要 |
PROBLEM TO BE SOLVED: To provide an electroabsorption optical modulator which optically realizes RZ coding with a simple structure. SOLUTION: Two electroabsorption optical modulation elements 15-1 and 15-2 are closely formed on the same substrate. A signal conductor which supplies a signal to the two optical modulation elements is formed by coplanar lines to make the signal conductor very thin. Signal transmission lines 17-1, 17-2 and auxiliary signal transmission lines 17-3, 17-4 are formed by using these coplanar lines within the space where condensing lenses 16A and 16B are opposed. Terminal resistors 19 are placed outside the range where the condensing lens are opposed by using the auxiliary signal transmission lines, and the condensing lenses are placed within the range of a predetermined size. |
