| 摘要 |
PURPOSE:To reduce cost by disposing in parallel directional couplers consisting of 2 inputs and 2 outputs and connecting the respective directional couplers so as to have an optical path length difference. CONSTITUTION:All the directional couplers 10-60 consisting of the 2 inputs and 2 outputs are disposed in parallel. The 2-output terminals of the 1st directional coupler 10 and the 2-input terminals of the 2nd directional coupler 20 are so connected as to have the optical path length difference. Further, one of the input terminals of the 3rd and 4th directional couplers 30, 50 is connected to the different terminals of the 2-output terminals of the 2nd directional coupler 20. The 5th directional coupler 40 is connected to the 3rd directional coupler 30 and the 6th directional coupler 60 is connected to the 4th directional coupler respectively in a manner as to have the optical path length difference. The constitution which is well balanced in the vertical and horizontal sizes is enabled by such parallel disposition of the directional couplers 10-60. The productivity is thereby improved and the cost is reduced. |
