# US 8,542,969 B2 · Low bend loss optical fiber

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- Number: US 8,542,969 B2
- Document ID: US8542969B2
- Status: Granted
- Kind: B2
- Application number: 13/030,308
- Filed: 2011-02-18
- Published: 2011-09-01
- Granted: 2013-09-24
- Earliest claimed: 2010-02-26
- Assignees: Corning Incorporated
- Applicants: Dana Craig Bookbinder; Ming-Jun Li; Pushkar Tandon
- Inventors: Dana Craig Bookbinder; Ming-Jun Li; Pushkar Tandon
- Web page: https://patentgrep.com/patent/US8542969B2

## CPC

- G02B 6/03627: {arranged - +}
- G02B 6/02014: {Effective area greater than 60 square microns in the C band, i.e. 1530-1565 nm}
- G02B 6/02242: {having a dispersion slope <0.06 ps/km/nm2}
- G02B 6/02266: {Positive dispersion fibres at 1550 nm}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An optical fiber having both low macrobend loss and low microbend loss. The fiber has a first inner cladding region having an outer radius r2>8 microns and refractive index Δ2 and a second outer cladding region surrounding the inner cladding region having refractive index Δ3, wherein Δ1>Δ3>Δ2. The difference between Δ3 and Δ2 is greater than 0.01. The fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm, and r1/r2 is greater or equal to 0.25.

## Claims

### Claim 1

An optical fiber comprising:
a germania doped central core region having outer radius r1 and refractive index Δ1
a cladding region comprising a first inner cladding region having an outer radius r2>8 microns and refractive index Δ2 and a second outer cladding region surrounding the inner cladding region and comprising refractive index Δ3, wherein Δ1>Δ3>Δ2, and wherein the difference between Δ3 and Δ2 is greater than 0.01, said fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm, and r1/r2 is greater or equal to 0.25.

### Claim 2 (depends on 1)

The optical fiber of claim 1, wherein the first inner cladding region contains less than 0.02 wt % fluorine.

### Claim 3 (depends on 1)

The optical fiber of claim 1, wherein the first inner cladding region is essentially free of fluorine and germania.

### Claim 4 (depends on 1)

The optical fiber of claim 1, wherein Δ3>Δ2 for a length extending from r2 to a radius of at least 30 microns.

### Claim 5 (depends on 1)

The optical fiber of claim 1, wherein r1/r2 is greater than 0.3.

### Claim 6 (depends on 1)

The optical fiber of claim 1, wherein the profile volume, V3 of the outer cladding region, calculated between the outer radius of the first inner cladding region and a radial distance of 30 um, is equal to:
V
3
=
2
⁢
∫
r
⁢
⁢
2
r
⁢
⁢
30
⁢
Δ
(
3
-
2
)
⁡
(
r
)
⁢
r
⁢
ⅆ
r
and |V3| is at least 5% Δμm2.

### Claim 7 (depends on 1)

The optical fiber of claim 1, wherein said fiber exhibits a bend loss of less than 0.75 dB/turn when wound upon on a 20 mm radius mandrel and exhibits a MAC number between 6.6 and 7.5.

### Claim 8 (depends on 1)

The optical fiber of claim 1, wherein the width of first inner cladding region r2-r1 is between 3 and 13 microns.

### Claim 9 (depends on 7)

The optical fiber of claim 7, wherein said fiber exhibits a bend loss of less than 1 dB/turn when wound upon on a 15 mm radius mandrel.

### Claim 10

A single mode optical fiber comprising
a central core region having outer radius r1 and refractive index Δ1
a cladding region comprising fluorine doped silica, said cladding comprising a first inner cladding region having outer radius r2 and refractive index Δ2 and a second outer cladding region having refractive index Δ3, wherein r1/r2 is greater than 0.25.

### Claim 11 (depends on 10)

The fiber of claim 10, wherein said core contains less than 2 wt percent Germania.

### Claim 12 (depends on 10)

The fiber of claim 10, said core is essentially free of germania.

### Claim 13 (depends on 10)

The fiber of claim 10, wherein said fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm.

### Claim 14 (depends on 10)

The optical fiber of claim 10, wherein the profile volume, V3 of the outer cladding region, calculated between the outer radius of the first inner cladding region and a radial distance of 30 um, is equal to:
V
3
=
2
⁢
∫
r
⁢
⁢
2
r
⁢
⁢
30
⁢
Δ
(
3
-
2
)
⁡
(
r
)
⁢
r
⁢
ⅆ
r
and |V3| is at least 5% Δμm2.

### Claim 15 (depends on 10)

The optical fiber of claim 10, wherein said fiber exhibits a bend loss of less than 0.75 dB/turn when wound upon on a 20 mm radius mandrel and exhibits a MAC number between 6.6 and 7.5.

### Claim 16 (depends on 10)

The optical fiber of claim 10, wherein the width of first inner cladding region r2-r1 is between 3 and 13 microns.

### Claim 17 (depends on 15)

The optical fiber of claim 15, wherein said fiber exhibits a bend loss of less than 1 dB/turn when wound upon on a 15 mm radius mandrel.