| 摘要 |
PURPOSE:To improve design characteristic and make handling easy by uniformly reducing the diameter of the clads of two optical single-mode fibers over the length (n) times the wavelength lambda, joining said parts in a parallel shape, and providing photocoupling holes at predetermined intervals in the coupled part thereby constituting a photodirectional coupler. CONSTITUTION:The parts 2, 4 of reduced clads obtained by etching two single- mode optical fibers 1, 3 with fluorine are joined by means of an adhesive agent, and are housed in the groove 10 of a dielectric substrate 9, further they are set by a matching agent. The joined part 6 is enclosed by resist and photocoupling holes 7 are made therein by exposure techniques. The intervals of the photocoupling holes 7 are so determined as to become l=lambda/4+ or -2nlambda. Here, lambda is the characteristic wavelength of the optical single-mode fiber 1. The photoelectric power distribution in the radial direction of this fiber for light propagation assumes a circle. Thereby, the photodirectional coupler of superior design characteristic and easy handling are obtained. |
