Optical fiber for the reduction of stimulated Brillouin scattering in high-power applications

Abstract

The invention relates to an optical fiber comprising a core and a cladding, wherein the core is made of a glass composition having a near-zero electrostrictive coefficient M.sub.11, to reduce the effect of stimulated Brillouin Scattering (SBS). The invention further relates to a compensation fiber segment for connection to a silica optical fiber, the compensation fiber segment being made of a glass composition having an electrostrictive coefficient that opposes that of the silica optical fiber so that an acoustic wave transmitted to compensation fiber segment from the silica optical fiber will generate an acoustic wave within the compensation fiber segment that is about 180 degrees out of phase with the that acoustic wave transmitted from the silica optical fiber, thereby minimizing the effect of stimulated Brillouin Scattering.

Claims

1. An optical fiber comprising a core and a cladding, wherein the core is made of a glass composition having a near-zero electrostrictive coefficient M.sub.11, and said glass composition is a silicate, aluminate, aluminosilicate, phosphate or borate glass composition.

2. The optical fiber according to claim 1, wherein the electrostrictive coefficient M.sub.11 of the core is from 0.10 to +1.0 m.sup.4/V.sup.2.

3. The optical fiber according to claim 1, wherein the electrostrictive coefficient M.sub.11 of the core is from 0.05 to +0.05 m.sup.4/V.sup.2.

4. The optical fiber according to claim 1, wherein the electrostrictive coefficient M.sub.11 of the core is from 0.01 to +0.01 m.sup.4/V.sup.2.

5. The optical fiber according to claim 1, wherein the core is made of a fluoro-phosphate glass.

6. The optical fiber according to claim 1, wherein the core is made of an alkali aluminosliicate glass.

7. The optical fiber according to claim 1, wherein the core is made of a silicate glass comprising 60 to 100 mol % SiO.sub.2, 0 to 20 mol % MO where MO is the sum of MgO, CaO, SrO, and BaO, and 0 to 20 mol % R.sub.2O where R.sub.2O is the sum of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, and Cs.sub.2O, and optionally contains Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2, GeO.sub.2, Nb.sub.2O.sub.5 and/or F.

8. The optical fiber according to claim 7, wherein said silicate glass contains Al.sub.2O.sub.3, B.sub.2O.sub.3, TiO.sub.2, GeO.sub.2, Nb.sub.2O.sub.5 and/or F.

9. The optical fiber according to claim 1, wherein the core is made of an aluminosilicate glass comprising 40 to 80 mol % SiO.sub.2, 10 to 30 mol % Al.sub.2O.sub.3, 0 to 10 mol % B.sub.2O.sub.3, 20 to 50 mol % MO where MO is the sum of MgO, CaO, SrO, and BaO, and 0 to 5 mol % R.sub.2O where R.sub.2O is the sum of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, and Cs.sub.2O, and optionally contains TiO.sub.2, GeO.sub.2, Nb.sub.2O.sub.5 and/or F.

10. The optical fiber according to claim 9, wherein said aluminosilicate glass contains TiO.sub.2, GeO.sub.2, Nb.sub.2O.sub.5 and/or F.

11. The optical fiber according to claim 1, wherein the core is made of a phosphate glass comprising 50 to 80 mol % P.sub.2O.sub.5, 0 to 25 mol % R.sub.2O where R.sub.2O is the sum of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, and Cs.sub.2O, 0 to 25 mol % MO where MO is the sum of MgO, CaO, SrO, and BaO, and 0 to 15 mol % Al.sub.2O.sub.3, and optionally contains SiO.sub.2, B.sub.2O.sub.3, TiO.sub.2, GeO.sub.2, Nb.sub.2O.sub.5 and/or F.

12. The optical fiber according to claim 11, said phosphate glass contains SiO.sub.2, B.sub.2O.sub.3, TiO.sub.2, GeO.sub.2, Nb.sub.2O.sub.5 and/or F.

13. The optical fiber according to claim 1, wherein the core has a refractive index of 1.4580 to 1.4620.

14. The optical fiber according to claim 1, wherein the core provides single-mode guiding and has NA below 0.2 and a diameter of 10-30 microns.

15. A compensation fiber segment for connection to a silica optical fiber, said compensation fiber segment comprising a core and a cladding, wherein said compensation fiber segment is made of a silicate, aluminosilicate, phosphate or borate glass composition having an electrostrictive coefficient that opposes that of the silica optical fiber so that an acoustic wave transmitted to compensation fiber segment from the silica optical fiber will generate an acoustic wave within the compensation fiber segment that is about 180 degrees out of phase with the that acoustic wave transmitted from the silica optical fiber.

16. The compensation fiber segment according to claim 15, wherein said core of said compensation fiber segment has an acoustic impedance and an acoustic radial profile similar to the silica optical fiber.

17. The compensation fiber segment according to claim 15, wherein said core of the compensation fiber segment has refractive index similar to the silica optical fiber.

18. The compensation fiber segment according to claim 15, wherein the core of said compensation fiber segment has a refractive index of 1.4580 to 1.4620.

19. The compensation fiber segment according to claim 15, wherein the core is made of a fluoro-phosphate glass.

20. The compensation fiber segment according to claim 15, wherein the core is made of an alkali aluminosliicate glass.

21. A fiber optical device comprising the compensation fiber segment according to claim 15 connected to at least one silica optical fiber.

22. The fiber optical device according to claim 21, wherein said compensation fiber segment is connected to two silica optical fibers.

Description

EXAMPLES

Example 1

(1) An optical fiber is prepared in accordance with conventional procedures from a preform. The optical fiber has a core with a diameter of 10-30 microns and two claddings, one to contain pump energy and the other to guide laser output (the outermost cladding may be glass or polymer). The core is made from a fluoro-phosphate or alkali aluminosliicate glass composition. The glass cladding has a similar composition but contains higher amounts of F, P, B, Li and/or Na or less amounts of Al or Si. The refractive index of the core is 1.46 and the refractive index of the cladding is 1.4585. The electrostrictive constant M11 of the core is near zero. The fiber length is up to several meters.

Example 2

(2) A compensation fiber segment is used to connect two silica optical fibers. The compensation fiber segment is prepared in accordance with conventional procedures from a preform. The compensation fiber segment has a core with a diameter of 10-30 microns and a cladding with a thickness of, for example, 50-100 microns The core and cladding are made of similar glass compositions containing, but the cladding contains B, or less amounts of Al or Si, or does not contain T. The refractive index of the core of compensation fiber segment is 1.46 and the refractive index of its cladding is 1.4585. The electrostrictive constant M11 of the core of the compensation fiber segment is near zero. The length of the compensation fiber segment is a few centimeters.

(3) The entire disclosure[s] of all applications, patents and publications, cited herein, are incorporated by reference herein.

(4) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(5) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.