OPTICAL COMMUNICATION DEVICE AND OPTICAL FIBER USED FOR IT, AND WORKING METHOD OF OPTICAL FIBER

摘要

PURPOSE:To form an optical fiber which has a reception terminal with high efficiency of optical coupling by making the diameter of the core part of the optical fiber greater at the opposite terminal to a light emitting semiconductor element than at other parts. CONSTITUTION:To obtain the large-diameter optical fiber 33, a multimode optical fiber is polished conically by a rotating grindstone 35 after a jacket is removed and only the tip is heated and fused by a hydrogen flame torch 36 to form a tip bead 5 having 40-50mum curvature (a). The cut end surface 37 on the opposite side to the tip bead 5 of the optical fiber 33 and the optical coupling side end surface 38 of a small-diameter core optical fiber 34 are made to face each other by aligning their optical axes by using a splicer and impurities are removed from the heat sealed surface by the discharge of a couple of discharging electrodes 39 while the heat sealed surface is provided with gentle curvature. While the discharging is carried on, both optical fibers 33 and 34 are brought into contact with each other to perform deposition. Then, the discharging is stopped and before curing starts, they are drawn lightly in such a direction that the bonded surfaces are separated, tapering the joint core part 40. Consequently, lens effect is obtained without reducing the area of photodetection to maximize condensating effect.