| 摘要 |
PURPOSE:To easily adjust the coupling center wavelength between cores with high accuracy by weighting an optical directional coupler and adjusting the coupling center wavelength. CONSTITUTION:When an optical fiber 10 is applied with torsional weight (exter nal force), two cores 11 and 12 are twisted at the lengthwise intermediate part of a multicore optical fiber 10 and lengthwise optical fiber components with propagation constants beta1 and beta2 become beta1costheta1 and beta2costheta2. Here, theta1 and theta2 are the angles between the traveling directions of light in the cores 11 and 12 and those cores 11 and 12 and have a relation 0<theta1<theta2<pi/2 and one core 11 is positioned inside of the other core 12 (on optical fiber center side), so costheta1>costheta2 holds. Therefore, when the multicore optical fiber 10 is twisted, the wavelength characteristic of its propagation constant varies and the coupling center wavelength lambda' is obtained. The degree of the twisting is adjusted to adjust the coupling center wavelength.
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