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US 10,883,860 B2Granted
Optical fiber sensor
AssigneeFujikura Ltd.
InventorsKenichi Ohmori, Koji Omichi, Shingo Matsushita, Kentaro Ichii
Life of this patent
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Abstract
An optical fiber sensor includes: a central core disposed at a center of an optical fiber; and an outer peripheral core that spirally surrounds the central core. The effective refractive index ne2 of the outer peripheral core is lower than the effective refractive index ne1 of the central core. A ratio between the effective refractive index ne2 and the effective refractive index ne1 matches a ratio between an optical path length of the central core and an optical path length of the outer peripheral core.
Claims7
An optical fiber sensor comprising:
- a central core disposed at a center of an optical fiber;
- and
- an outer peripheral core that spirally surrounds the central core, wherein
- Expression (1) is satisfied:
- n
- e
-
-
- 1
- ×
- (
- 1
- f
- w
- -
- B
- )
- <
- n
- e
-
-
- 2
- ×
- (
- 1
- f
- w
- +
- A
- )
- <
- n
- e
-
-
- 1
- ×
- (
- 1
- f
- w
- +
- B
- )
- (
- 1
- )
- where d is a distance between the central core and the outer peripheral core,
- fw is a number of spirals of the outer peripheral core per unit length of the optical fiber,
- ne1 is an effective refractive index of the central core,
- ne2 is an effective refractive index of the outer peripheral core,
- A
- =
- (
- 1
- f
- w
- )
- 2
- +
- (
- 2
-
-
- π
-
-
- d
- )
- 2
- -
- 1
- f
- w
- ,
-
- and
- B
- =
- A
- 1
- +
- A
- ·
- f
- w
- .
85 more elements
Dependencies are inferred from the claim text.