| 摘要 |
PURPOSE:To make an isolation large, and also, to reduce the manufacturing cost by bringing five pieces of directional couplers having input two- and output two-ports to prescribed connection, and also, setting the structural dimensions of each coupler of a second, a third, and a fourth, a fifth to the same. CONSTITUTION:To output ports of the first coupler 4a of five pieces of directional couplers 4a-4e having input two- and output two-ports, input ports of the second and the third couplers 4b, 4c are connected, and to output ports of the second and the third couplers 4b, 4c, input ports of the fourth and the fifth couplers 4d, 4e are connected. Also, structural dimensions of the second and the third couplers 4b, 4c and the fourth and the fifth couplers 4d, 4e are set to the same. An optical signal of wavelength lambda1 and that of wavelength lambda2 are demultiplexed to an output port 1e-0 and an output port 2d-0, respectively. As a result, the optical signal passes through three couplers, therefore, an isolation becomes large, and since the structural dimensions are the same, the manufacturing cost can be reduced. |
