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US 6,647,192 B1Granted
Optical fiber
AssigneeMitsubishi Cable Industries, Ltd.
InventorsMinoru Yoshida, Kazuo Imamura, Tadahiko Nakai, Yasuhide Sudo
Life of this patent
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Abstract
A long period grating (8) by which an excitation light propagated through the 2nd core (4) of a double-core type optical fiber composed of the 2nd core (4) formed on the outer circumference of the 1st core (2) is guided into the 1st core (2) is formed on the 1st core (2) to improve an excitation efficiency.
Claims4
An optical fiber having a 1st core doped with a rare-earth element and a 2nd core formed on an outer circumference of said 1st core, in which a refractive index thereof is set to be smaller than that of said 1st core,
- wherein a long period grating for guiding an excitation light propagating through said 2nd core into said 1st core by means of mode coupling is formed in said 1st core.
Dependencies are inferred from the claim text.