JPS5635113A - Photocoupler - Google Patents

Abstract

PURPOSE:To make the efficiency and productivity of a photocoupler higher by making each of a plurality of optical fibers once slender then making them thick again thence forming the end faces of a photocoupling region. CONSTITUTION:Three optical fibers are so formed as to satisfy b<a<c where the sum of the outside diameters of the three optical fibers is defined as (c), the long diameter of the finest portion as (b) and the long diameter of an end face 3 as (a). The ray 17 incident from a light source 14 advances while making total reflection on the clad 12 on the outer side; the angle at which it advances becomes small in the portion of a fiber bundle 16 and the coupling efficiency becomes high. In addition, light 18 enters the core at the center but in the portion of a fiber bundle 15, it flies to the core on the outer side and is confined in the core on the outer side. Since in this way the output of the fiber at the center is decreased and more light is distributed to the other fibers, the deviation of distribution ratios is decreased. The manufacturing method simply entails placing optical fibers on one row, pulling them under heating, cutting them at a suitable place and polishing their end faces. In this way, the photocoupler of high efficiency and superior productivity is obtained.