| 摘要 |
PURPOSE:To facilitate the manufacture of an optical branching device and to prevent propagated light from deteriorating in quality by branching part of the propagated light by total reflection. CONSTITUTION:The 1st optical waveguide 1 which has its projection surface divided into two according to a branching ratio and has a reflecting layer 2 on one of the two divided projection surfaces slantingly to the optical axis of the propagated light, the 2nd optical waveguide 3 which is connected to the other projection end surface, and th 3rd optical waveguide 4 which is connected nearby the projection end of the 1st optical waveguide 1 and guides the light branched by the reflecting surface 2 are provided on the same substrate. A means which reflects part of useful guided light is the reflecting layer 2 formed at part of the projection end surface of an incidence-side waveguide and constitution which branches part of the propagated light through the total reflection of the reflecting layer 2 is employed, so the branching ratio and a branching angle can be selected over extremely wide ranges and the influence of the branching on the propagated light such as mode conversion and propagation loss is a little.
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