Optical Fiber
First Claim
1. An optical fiber comprising at least:
- a central core portion having a maximum refractive index N1 and an outer diameter 2a;
a depressed portion, provided on an outer periphery of said central core portion, having a minimum refractive index N2 and an outer diameter 2b; and
a cladding portion, provided on an outer periphery of said depressed portion, having a maximum refractive index N3,wherein said respective maximum refractive indices of said central core portion, said depressed portion and said cladding portion satisfy the following relationship;
N1>
N3>
N2,wherein a relative refractive index difference Δ
1 of said central core portion with respect to said cladding portion is larger than 1.0%, and a relative refractive index difference Δ
2 of said depressed portion with respect to said cladding portion is smaller than −
0.3%, andwherein, at a wavelength of 1.05 μ
m, the second derivative β
2 of the propagation constant P with respect to frequency ω
is positive, the third derivative β
3 of the propagation constant P with respect to frequency ω
is negative, and the ratio (β
3/β
2) of the third derivative β
3 to the second derivative β
2 is −
0.002 ps or less.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention relates to an optical fiber for light pulse expansion in which the ratio (β3,β2) of the third derivative β3 to the second derivative β2 is negative, the absolute value thereof is large, and the absolute value of the second derivative β2 is also large. Such an optical fiber comprises at least a central core portion having a maximum refractive index N1 and an outer diameter 2a , a depressed portion, provided on the outer periphery of the central core portion, having a minimum refractive index N2 and an outer diameter 2b, and a cladding portion, provided on the outer periphery of the depressed portion, having a maximum refractive index N3. The respective maximum refractive indices of the central core portion, the depressed portion and the cladding portion satisfy the relationship “N1>N3>N2”. The relative refractive index difference Δ1 of the central core portion with respect to the cladding portion is larger than 1.0%, and the relative refractive index difference Δ2 of the depressed portion with respect to the cladding portion is smaller than −0.3%. At the wavelength of 1.05 μm, the second derivative β2 of the propagation constant β with respect to frequency ω is positive, the third derivative β3 of the propagation constant β with respect to frequency co is negative, and the ratio (β3/β2) is −0.002 ps or less.
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Citations
9 Claims
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1. An optical fiber comprising at least:
- a central core portion having a maximum refractive index N1 and an outer diameter 2a;
a depressed portion, provided on an outer periphery of said central core portion, having a minimum refractive index N2 and an outer diameter 2b; and
a cladding portion, provided on an outer periphery of said depressed portion, having a maximum refractive index N3,wherein said respective maximum refractive indices of said central core portion, said depressed portion and said cladding portion satisfy the following relationship;
N1>
N3>
N2,wherein a relative refractive index difference Δ
1 of said central core portion with respect to said cladding portion is larger than 1.0%, and a relative refractive index difference Δ
2 of said depressed portion with respect to said cladding portion is smaller than −
0.3%, andwherein, at a wavelength of 1.05 μ
m, the second derivative β
2 of the propagation constant P with respect to frequency ω
is positive, the third derivative β
3 of the propagation constant P with respect to frequency ω
is negative, and the ratio (β
3/β
2) of the third derivative β
3 to the second derivative β
2 is −
0.002 ps or less.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
- a central core portion having a maximum refractive index N1 and an outer diameter 2a;
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8. An optical fiber coil including an optical fiber according to claim 1, while being winded into a coil shape.
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9. An optical fiber coil according to claim 8, wherein the minimum wound diameter of said optical fiber is 120 mm or less.
Specification