Optical fiber structure and a method of producing thereof
View Patent ↗An optical waveguide including a core, a buffer surrounding the core, and a cladding surrounding the buffer. The core, the buffer and the cladding include silica glass. A refractive index of the buffer is substantially equal to a refractive index of pure amorphous silica glass. The buffer may reduce bubble formation during manufacturing and may facilitate splicing of the waveguide. A numerical aperture of the waveguide may be fine-tuned by adjusting a radial dimension of the buffer in order to compensate variations in the refractive index of the core.
1. An optical waveguide, comprising:
a core doped with at least one light-amplifying dopant;
a buffer surrounding said core; and
a cladding surrounding said buffer,
wherein said core, said buffer, and said cladding comprise silica glass, wherein a refractive index of said buffer is substantially equal to a refractive index of pure amorphous silica glass, wherein a refractive index of said cladding is greater than the refractive index of said buffer, wherein a ratio of a radial dimension of said buffer to a radius of said core is in a range of 0.05 to 0.4, and wherein an effective mode area of said waveguide is greater than or equal to 200 μm 2 .
2. The optical waveguide according to claim 1 , wherein the radius of said core is greater than or equal to 3 μm.
3. The optical waveguide according to claim 1 , wherein a numerical aperture of said optical waveguide is in a range of 0.05 to 0.08.
4. The optical waveguide according to claim 3 , wherein the numerical aperture of said optical waveguide is in the range of 0.05 to 0.065.
5. The optical waveguide according to claim 1 , wherein the radial dimension of the buffer is smaller than or equal to 5 μm.
6. A method for producing an optical waveguide, said optical waveguide comprising:
a core doped with at least one light-amplifying dopant,
a buffer surrounding said core, and
a cladding surrounding said buffer,
wherein said core, said buffer, and said cladding comprise silica glass, wherein a refractive index of said buffer is substantially equal to a refractive index of pure amorphous silica glass, wherein a refractive index of said cladding is greater than the refractive index of said buffer, wherein a ratio of a radial dimension of said buffer to a radius of said core is in a range of 0.05 to 0.4, and wherein an effective mode area of said waveguide is greater than or equal to 200 μm 2 ,
said method comprising:
adjusting the radial dimension of said buffer so as to tune a cut-off wavelength of single mode operation of said optical waveguide to a predetermined value.
7. The method according to claim 6 , wherein the radial dimension of said buffer is adjusted according to a refractive index of said core and according to the refractive index of said cladding.
8. The method according to claim 6 , wherein the radial dimension of said buffer is adjusted such that a difference between a predetermined numerical aperture and an attained numerical aperture is smaller than or equal to 0.005.
9. The method according to claim 6 , further comprising:
providing a predetermined radius of said core.
10. The method according to claim 9 , wherein the radial dimension of said buffer is selected to correspond to a refractive index of said core and/or to the refractive index of said cladding so as to compensate for variations in the refractive index of said core and/or in the refractive index of said cladding.
11. A method for producing an optical waveguide, said optical waveguide comprising
a core doped with at least one light-amplifying dopant,
a buffer surrounding said core, and
a cladding surrounding said buffer,
wherein said core, said buffer, and said cladding comprise silica glass, and a refractive index of said buffer is smaller than or equal to a refractive index of pure amorphous silica glass, a refractive index of said cladding is greater than the refractive index of said buffer, a ratio of a radial dimension of said buffer to a radius of said core is in a range of 0.05 to 0.4, and an effective mode area of said waveguide is greater than or equal to 200 μm 2 ,
said method comprising:
adjusting the radial dimension of said buffer so as to tune a cut-off wavelength of single mode operation of said optical waveguide to a predetermined value.
12. The method according to claim 11 , wherein the radial dimension of said buffer is adjusted according to a refractive index of said core and according to the refractive index of said cladding.
13. The method according to claim 11 , wherein the radial dimension of said buffer is adjusted such that the difference between a predetermined numerical aperture and an attained numerical aperture is smaller than or equal to 0.005.
14. The method according to claim 11 , further comprising:
providing a predetermined radius of said core.
15. The method according to claim 11 , wherein the radial dimension of said buffer is selected to correspond to the refractive index of said core and/or to the refractive index of said cladding so as to compensate for variations in the refractive index of said core and/or in the refractive index of said cladding.
16. A light-amplifying optical waveguide, comprising:
a core doped with at least one light-amplifying dopant;
a buffer surrounding said core; and
a cladding surrounding said buffer,
wherein said core, said buffer, and said cladding comprise silica glass, wherein a refractive index of said buffer is substantially equal to a refractive index of pure amorphous silica glass, wherein a refractive index of said cladding is greater than the refractive index of said buffer, wherein a ratio of a radial dimension of said buffer to a radius of said core is in a range of 0.05 to 0.4, and wherein an effective mode area of said waveguide is greater than or equal to 200 μm 2 .
17. The optical waveguide according to claim 16 , wherein the radius of said core is greater than or equal to 3 μm.
18. The optical waveguide according to claim 16 , wherein a numerical aperture of said optical waveguide is in a range of 0.05 to 0.08.
19. The optical waveguide according to claim 16 , wherein a numerical aperture of said optical waveguide is in a range of 0.05 to 0.065.
20. The optical waveguide according to claim 16 , wherein the radial dimension of the buffer is smaller than or equal to 5 μm.
21. A method for producing an optical waveguide, said optical waveguide comprising
a core doped with at least one light-amplifying dopant,
buffer surrounding said core, and
a cladding surrounding said buffer,
wherein said core, said buffer, and said cladding comprise silica glass, and a refractive index of said buffer is substantially equal to a refractive index of pure amorphous silica glass, a refractive index of said cladding is greater than the refractive index of said buffer, a ratio of a radial dimension of said buffer to a radius of said core is in the range of 0.05 to 0.4, and an effective mode area of said waveguide is greater than or equal to 200 μm 2 ,
said method comprising:
adjusting the radial dimension of said buffer so as to attain a predetermined numerical aperture of said optical waveguide.
22. A method for producing an optical waveguide, said optical waveguide comprising
a core doped with at least one light-amplifying dopant,
a buffer surrounding said core, and
a cladding surrounding said buffer,
wherein said core, said buffer, and said cladding comprise silica glass, and a refractive index of said buffer is smaller than or equal to a refractive index of pure amorphous silica glass, a refractive index of said cladding is greater than the refractive index of said buffer, the ratio of a radial dimension of said buffer to a radius of said core is in a range of 0.05 to 0.4, and an effective mode area of said waveguide is greater than or equal to 200 μm 2 ,
said method comprising:
adjusting the radial dimension of said buffer so as to attain a predetermined numerical aperture of said optical waveguide.
23. The method according to claim 22 , further comprising:
providing a rod doped with at least one light-amplifying dopant;
sintering the rod after the rod has been coated with a first glass layer comprising substantially pure silica glass;
forming a perform comprising the rod, the first glass layer, and a second glass layer; and
drawing the optical waveguide from the preform.
24. The method according to claim 22 , further comprising:
providing a rod doped with at least one light-amplifying dopant;
selecting the radial dimension of a first glass layer to the radius of the rod according to the refractive index of the rod, wherein the first glass layer comprises substantially pure silica glass;
forming a perform comprising the rod and the first glass layer; and
drawing the optical waveguide from the preform.