Highly rare-earth-doped optical fibers for fiber lasers and amplifiers
AssigneeImra America, Inc.
InventorsLiang Dong, Martin E. Fermann, Hugh McKay, Libin Fu, Shigeru Suzuki
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Abstract
Various embodiments described herein comprise a laser and/or an amplifier system including a doped gain fiber having ytterbium ions in a phosphosilicate glass. Various embodiments described herein increase pump absorption to at least about 1000 dB/m-9000 dB/m. The use of these gain fibers provide for increased peak-powers and/or pulse energies. The various embodiments of the doped gain fiber having ytterbium ions in a phosphosilicate glass exhibit reduced photo-darkening levels compared to photo-darkening levels obtainable with equivalent doping levels of an ytterbium doped silica fiber.
Claims38
An optical fiber comprising:
- a rare earth doped glass comprising silica, a rare-earth dopant, phosphorus, and aluminum, wherein the concentration of the rare-earth dopant is at least about 0.5 mol %;
- said optical fiber configured to have a peak absorption greater than about 3000 dB/m at a pump wavelength and a gain greater than about 0.5 dB/cm at an emission wavelength, and
- wherein the phosphorus in the rare-earth doped glass has a concentration such that a saturated value of photo-darkening loss in the optical fiber is less than about 10 dB/m at said emission wavelength.
A system comprising:
- a fiber amplifier comprising an amplifier material configured to amplify radiation in a first wavelength range having a signal wavelength, the amplifier material comprising rare-earth dopant, phosphorus, and aluminum, wherein the phosphorus in the amplifier material has a concentration such that a saturated value of photo-darkening loss in the amplifier material is less than about 10 dB/m at the signal wavelength;
- and
- a fiber pump laser comprising a laser material configured to produce radiation in a second wavelength range having a pump wavelength, said fiber pump laser configured to core pump the fiber amplifier,
- wherein an emission cross section of the pump laser material at the pump wavelength is about 10% greater than an emission cross section of the amplifier material at the pump wavelength.
An optical amplifier, comprising:
- a pump source;
- and
- a gain fiber, said gain fiber comprising:
- a cladding comprising silica;
- a core comprising a rare-earth dopant, phosphorus, and aluminum,
- wherein the concentration of the rare-earth dopant is at least about 0.5 mol %, and said gain fiber has a peak absorption greater than about 3000 dB/m at a pump wavelength and a gain greater than about 0.5 dB/cm at an emission wavelength, and
- wherein the phosphorus in the gain fiber has a concentration such that a saturated value of photo-darkening loss of the gain fiber is less than about 10 dB/m at the emission wavelength.
An optical fiber comprising:
- a rare earth doped core having a core radius ρ;
- a first cladding disposed about said core;
- and
- a second cladding disposed about said first cladding,
- said first cladding having an outer radius ρ1, said core and said first cladding having a difference in index of refraction Δn, and said first cladding and said second cladding having a difference in index of refraction Δn1,
- wherein (i) less than 10 modes are supported in said core, (ii) the first cladding radius, ρ1, is greater than about 1.1ρ and less than about 2ρ, and (iii) the refractive index difference between said first cladding and said second cladding, Δn1, is greater than about 1.5 Δn and less than about 50 Δn,
- wherein said optical fiber comprises silica, a rare-earth dopant, phosphorus, and aluminum, and the concentration of the rare-earth dopant is at least about 0.5 mol %, said optical fiber having a peak absorption greater than about 3000 dB/m to about 9000 dB/m at a pump wavelength, and
- wherein the phosphorus in the rare-earth doped core has a concentration such that the saturated value of the photo-darkening loss of the optical fiber is less than about 10 dB/m at an emission wavelength.
Dependencies are inferred from the claim text.