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US 4,904,040 AGranted
Optical waveguide coupler for monitoring
AssigneeSeiko Instruments Inc.
InventorsToshiharu Takesue, Hiroyoshi Yamamoto
Life of this patent
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Abstract
An optical waveguide coupler comprises at least two optical waveguides such as optical fibers closely spaced apart for allowing light propagating in one optical waveguide to couple into the other. Optical waveguide portions of the waveguides are made of materials having different refractive indices respectively. The feature stabilizes the splitting ratio against a slight change in coupling length, whereby the control of the coupling ratio during manufacture becomes easy, and deviations in splitting ratio can be greatly reduced.
Claims8
An optical waveguide coupler comprising:
- at least two light propagating optical portions closely spaced from each other for allowing light propagating in one of said optical portions to couple into one or more others of said optical portions, said optical portions comprising materials having different refractive indices respectively such that the splitting ratio of the coupler is reduced to a selected maximum at predetermined multiples of the coupling length of the coupler.
Dependencies are inferred from the claim text.