Bend insensitive single mode fiber

• US 8,750,664 B2
• Filed: 07/03/2009
• Issued: 06/10/2014
• Est. Priority Date: 08/20/2008
• Status: Active Grant

• Current Assignee: Futong Group Company Limited (Hangzhou Futong Investment Co. Ltd.)
• Original Assignee: Futong Group Company Limited (Hangzhou Futong Investment Co. Ltd.)
• Inventors: Zhang, Liyong, Lu, Weimin, Wu, Haigang, Li, Qunxing, Huang, Xiaopeng
• Primary Examiner(s): Le, Uyen Chau N
• Assistant Examiner(s): Smith, Chad
• Application Number:
  US13/059,971
• Publication Number:
  US 20110142404A1
• Time in Patent Office: 1,803 Days
• Field of Search: None
• US Class Current: 385/127
• CPC Class Codes: G02B 6/02395 Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104
• CPC Class Codes: G02B 6/0281 Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core G02B6/0288, G02B6/0286 take precedence
• CPC Class Codes: G02B 6/03611 Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
• CPC Class Codes: G02B 6/03627 arranged - +

Abstract

This invention discloses a bend insensitive single mode fiber, which is composed by a bare glass fiber with a round cross section and two resin protective layers with circular cross sections surrounding the outer of the bare glass fiber. It is characterized in that the bare glass fiber is composed by a core layer with a round cross section and two claddings with circular cross sections. The refractive index of the core layer is higher than the index of the two claddings and the refractive index difference between the core layer and the first cladding is larger than the difference between the first and second claddings. The second cladding is made of pure SiO₂. The refractive index profile of the core layer follows a power function, and the refractive index profile of the two claddings follow a ladder-type distribution. The loss of the invented fiber is insensitive to the bending of the fiber, which meets the requirements of ITU.T G.657.A and G.657.B standards, respectively. It is applicable to the Fiber To The Home (FTTH) and other local area network and the access network systems.

Claims

1. A bend insensitive single mode comprising:

a bare glass fiber (11) with a round cross section and two resin protective layers (12, 13) with circular cross sections surrounding the outer of the bare glass fiber (11);

wherein

the bare glass fiber (11) is composed by a core layer (111) with a round cross section and two claddings (112, 113) with circular cross sections,

a refractive index of the core layer (111) is higher than refractive indexes of the two claddings (112, 113);

a refractive index difference (Δ

₁) between the core layer (111) and the first cladding (112) Δ

₁ is between 0.0033˜

0.0072, a refractive index difference (Δ

₂) between the first cladding (112) and second (113) claddings Δ

₂ is between −

0.0016˜

0, a thickness (a) of the core layer (111) is between 2.7˜

4.1 μ

m, a thickness (b) of the first cladding (112) is between 0.5˜

2.3 μ

m and a thickness (c) of the second cladding (113) is between 56.7˜

59.8 μ

m; and

the second cladding (113) is made of pure SiO₂, a refractive index profile of the core layer (111) follows a power function distribution, and the refractive index profiles of the two claddings (112 and 113) follow a ladder-type distribution.

2. The bend insensitive single mode fiber according to claim 1, wherein a diameter of the bare glass fiber (11) is between 124.3˜

125.7 μ

m, for the first resin protective layer (12), a thickness is 38±

1 μ

m, Young'"'"'s modulus is 1.1±

0.1 MPa;

for the second resin protective layer (13), a thickness is 22±

1 μ

m, Young'"'"'s modulus is 700±

50 MPa;

a diameter of the bare glass fiber is 125±

1 μ

m and total diameter of the fiber is 242±

7 μ

m.

3. The bend insensitive single mode fiber according to claim 1, wherein power exponents of distributed power function of refractive index profile of the core layer (111) near a center part and near the first cladding (112) part are 3˜

5 and −

9˜

−

8 respectively.

4. The bend insensitive single mode fiber according to claim 1, wherein the refractive index difference (Δ

₁) of the core layer (111) and the first cladding (112) is between 0.0058˜

0.0072;

the refractive index difference (Δ

₂) of the first (112) and second (113) claddings is between −

0.0016˜

−

0.0008;

a thickness (a) of the core layer (111) is between 2.8˜

3.2 μ

m, a thickness (b) of the first cladding (112) is between 0.8˜

2.1 μ

m and a thickness (c) of the second cladding (113) is between 57.1˜

58.9 μ

m;

a diameter of the bare glass fiber is 125±

1 μ

m and the outer diameter of the fiber is 242±

7 μ

m.

5. The bend insensitive single mode fiber according to claim 4, wherein a mode field diameter (MFD) is 6.5±

0.5 μ

m at 1310 nm and a cutoff wavelength (λ

_c) is between 1180˜

1330 nm;

when measured by winding ten turns with a radius of 15 mm, a macro-bending loss of the fiber is less than 0.03 dB at 1550 nm and a macro-bending loss is less than 0.1 dB at 1625 nm;

when measured by winding one turn with a radius of 10 mm, a macro-bending loss of the fiber is less than 0.1 dB at 1550 nm and a macro-bending loss is less than 0.2 dB at 1625 nm;

when measured by winding one turn with the radius of 7.5 mm, a macro-bending loss of the fiber is less than 0.5 dB at 1550 nm and a macro-bending loss is less than 1.0 dB at 1625 nm.