| 摘要 |
PURPOSE:To attain no hit switching, by adjusting the degree of coupling of a connection part so that the sum of light outputs from two optical fibers to be switched, connected between a pair of facing optical fiber branching circuits, goes to a regulated level, and switching the optical fiber when the degree of coupling on one side goes to zero finally. CONSTITUTION:It is assumed that the branch ratios of two optical fiber branching circuits 3 are set as 1:x, and 1:y. A light amplifier 12 has light amplification degree of 1/xy, that is the inverse number of the product (xy) of the branch ratios, and the amplification degree possible to compensate the difference of loss between optical fibers 1-A and 1-C. And the degree of coupling of two variable coupling connection parts 5-1 and 5-2 are synchronized and changed by a signal from a controller 13. The degree of coupling of the variable coupling connection part 5-1 is reduced, and adversely, that of the variable coupling connection part 5-2 is increased, then, branching loss is compensated by the amplifier. The light output from an optical fiber 1-2 becomes the sum of the light output from the optical fiber 1-A, and the light output from the optical fiber 1-C, then it is regulated in a time aspect. By reducing the degree of coupling of the variable coupling connection part 5-1, and increasing that of the variable coupling connection part 5-2, keeping the rgulated level of the light output, switching from the optical fiber 1-A to the optical fiber 1-C can be performed. |
