| 摘要 |
PURPOSE:To improve the utilizing efficiency of an optical branching filter to be used for a dendrite type optical network system by disposing plural sheets of multilayered dielectric film filters having different transmittances and sliding the filter to vary the branching ratio. CONSTITUTION:This optical branching filter varies the branching ratio by sliding the multilayered dielectric film filter 20 disposed flatly with plural sheets of the multilayered dielectric film filter having the transmittances meeting the desired branching ratios in the directions perpendicular to the axis of a self- focusing lens 19. The light which is emitted from an optical fiber 16, is made into parallel light by the lens 19 and is reflected by the filter 20 is condensed to an optical fiber 18. The light which is transmitted through the filter 20, is reflected by a reflecting mirror 21 and is again transmitted through the filter 20 is condensed to an optical fiber 17. The light from the fiber 16 can be thereby branched to the fibers 17 and 18 respectively. The optional setting of the branching ratio is further made possible by selecting the transmittance of the filter 20.
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