| 摘要 |
PURPOSE:To obtain a branching circuit which has a wide angle and a low loss although its constitution is simple by composing the circuit of a straight transmission line and a couple of branching transmission lines and arranging them so that the branching transmission lines face the linear transmission line closely. CONSTITUTION:An end part of the straight transmission line 1 is tapered having the sectional area reduced gradually and optical transmission lines 1a and 1b are formed at mutually opposite parts. The couple of branching transmission lines 2 and 2 are equal in refractive index to the straight transmission line 1 and slanting optical transmission lines 2a and 2a corresponding to the taper of the optical transmission lines 2 and 2 are provided at end parts of the branching transmission lines 1a and 1a. Those straight transmission line 1 and branching transmission lines 2 and 2 are so arranged that the respective optical transmission lines 1a and 1a and 2a and 2a are close to each other, but their distance (d) is reduced as much as possible and preferably about a submultiple of the wavelength of light to be transmitted. |
