| 摘要 |
PURPOSE:To obtain an optical branching device having a uniform characteristic by inserting a core and a clad into a cylinder body and heating them to stretch them in the lengthwise direction as one body and cutting a base material, which is obtained in this manner, in the direction vertical to the lengthwise direction. CONSTITUTION:One side face 3A in the lengthwise direction of a core 3 consisting of a high-refractive index transparent material makes 120 deg. to an adjacent surface, and side faces 3A, 3A, and 3A of cores 3, 3, and 3 are butted to one another, and cores are combined radially in this manner and are arranged in a cylinder body 6. Clads 4 which have almost the same shape as spaces 7, 7, and 7 and consist of materials having a refractive index lower than that of cores 3 are inserted there. This cylinder body is heated in a heating furnace to soften cores and clads, and a tension is applied to the front end to stretch them into one body, and the part of the cylinder body is removed by grinding to produce a branching device base material 8. This base material 8 is cut to a prescribed thickness in the direction vertical to the lengthwise direction to form disc bodies 9, and disc-shaped transparent plates 5 and 5 having almost the same refractive index as clads 4 are stuck to both faces of this disc body 9, thus producing the optical branching device. |
