Radiation-resistant rare-earth-doped optical fiber and method of radiation-hardening a rare-earth-doped optical fiber
A radiation-resistant optical fiber includes at least one core and at least one first cladding surrounding the core. The core includes a phosphosilicate matrix, the core being rare-earth doped, the rare earth being chosen from erbium, ytterbium, neodymium, thulium or erbium-ytterbium of thulium-holmium codoped and the core is cerium codoped. Also described is a method for radiation-hardening an optical fiber including the core having a phosphosilicate matrix, the core being rare-earth doped, the rare earth being chosen from erbium, ytterbium, neodymium and thulium, or erbium-ytterbium or thulium-holmium codoped, and including a step of cerium codoping the core of the fiber.
1. A radiation-resistant optical fiber which is resistant to ionizing radiations, comprising:
at least one core ( 1 ); and
at least one first cladding ( 2 ) surrounding said core ( 1 ), wherein,
said core ( 1 ) comprises a phosphosilicate matrix,
said core ( 1 ) is doped with a rare earth element chosen from erbium, ytterbium, neodymium, thulium, or being erbium-ytterbium codoped or thulium-holmium codoped, and
said core ( 1 ) is codoped with cerium, and a phosphorus concentration is between 2 and 10 atomic %, and the cerium concentration is between 500 and 10000 ppm.
2. The optical fiber according to claim 1 , characterized in that the core is erbium doped or erbium-ytterbium codoped and in that the ratio between the erbium concentration and the cerium concentration (Er/Ce) in the fiber core is between 0.05 and 50.
3. The optical fiber according to claim 2 , characterized in that the core is erbium-ytterbium codoped and in that the ratio of the concentrations Yb/Er in the core of the fiber is between 5 and 50.
4. The optical fiber according to claim 3 , characterized in that the erbium concentration is between 100 and 1000 ppm, the ytterbium concentration is between 500 and 10000 ppm.
5. The optical fiber according to claim 1 , characterized in that the fiber comprises a second cladding surrounding the first cladding.
6. The optical fiber according to claim 1 , characterized in that the core further comprises hydrogen and/or fluorine.
7. The optical fiber according to claim 1 , characterized in that the fiber is a polarizing or polarization-maintaining fiber.
8. The optical fiber according to claim 1 , characterized in that the fiber is a micro-structured fiber or a photonic fiber comprising a cladding made of hollow capillaries or the fiber comprises a bandgap structure, or the fiber is a large-mode-area fiber.
9. A radiation-resistant optical-fiber amplifier comprising an optical fiber according to claim 1 .
10. A radiation-resistant fiber laser comprising an optical fiber according to claim 1 .
11. A method for radiation-hardening an optical fiber to ionizing radiations, comprising a phosphosilicate-matrix core, said core being doped with a rare earth chosen from erbium, ytterbium, neodymium, thulium, or being erbium-ytterbium codoped or thulium-holmium codoped; and a step of cerium codoping said core of the optical fiber so that a phosphorus concentration is between 2 and 10 atomic %, and the cerium concentration is between 500 and 10000 ppm.
12. The method according to claim 11 , characterized in that it comprises an additional step of fluorine codoping the core and/or the cladding of said fiber.
13. The method according to claim 11 , characterized in that it comprises an additional step of hydrogenating said optical fiber.
14. A method for manufacturing an active, radiation-resistant optical device using a rare-earth-doped optical fiber comprising a phosphosilicate-matrix core, said core being doped with a rare earth chosen from erbium, ytterbium, neodymium, thulium, or being erbium-ytterbium or thulium-holmium codoped, said core being cerium codoped so that said fiber has an increased radiation resistance, wherein a phosphorus concentration is between 2 and 10 atomic %, and the cerium concentration is between 500 and 10000 ppm.
15. The method according to claim 14 , characterized in that said optical device is chosen from: a rare-earth-doped optical-fiber amplifier, a fiber laser, a wideband source.
16. The optical fiber according to claim 2 , characterized in that the core is erbium-ytterbium codoped and in that the ratio of the concentrations Yb/Er in the core of the fiber is between 5 and 50.
17. The method according to claim 12 , characterized in that it comprises an additional step of hydrogenating said optical fiber.
18. The optical fiber according to claim 1 , wherein,
said core is erbium-ytterbium codoped, and
said at least one first cladding surrounding said core is a fluorinated-silica double-cladding having a numerical aperture (N.A.) higher than 0.40.
19. The optical fiber according to claim 18 , wherein the ratio of the concentrations Yb/Er in said core is between 12 and 25.
20. The optical fiber according to claim 18 , wherein the concentration ratio Yb/Ce is between 0.1 and 10 in said core.