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US 7,440,167 B2Granted
Optical fiber for Raman amplification, optical fiber coil, Raman amplifier, and optical communication system
AssigneeFurukawa Electric Co., Ltd.
InventorsYuki Taniguchi, Yoshihiro Emori, Ryuichi Sugizaki, Atsushi Oguri, Takeshi Yagi
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Abstract
An optical fiber for Raman amplification amplifies a signal light with a pumping light. A chromatic dispersion at a wavelength of 1,550 nm is in a range between −70 ps/nm/km and −30 ps/nm/km. Raman gain efficiency with a pumping light of 1,450 nm is equal to or more than 5 (W×km)−1. Nonlinear coefficient at the wavelength of 1,550 nm is equal to or less than 5.0×10−9 W−1. Zero-dispersion wavelength is neither at a wavelength of the signal light nor at a wavelength of the pumping light. Cut-off wavelength is equal to or less than the wavelength of the pumping light.
Claims12
A Raman amplifier that Raman amplifies a signal light, the Raman amplifier comprising:
- an input unit to which the signal light is input;
- an output unit from which amplified signal light is output;
- a first optical fiber for Raman amplifying the signal light with a pumping light provided in at least a part between the input unit and the output unit;
- and
- a pumping light source that supplies a pumping light to the first optical fiber, wherein
- a chromatic dispersion of the first optical fiber at a wavelength of 1,550 nanometers is in a range between −70 ps/nm/km and −30 ps/nm/km,
- a Raman gain efficiency of the first optical fiber with a pumping light of 1,450 nanometers is equal to or more than 5 (W×km)−1,
- a nonlinear coefficient of the first optical fiber at the wavelength of 1,550 nanometers is equal to or less than 5.0×10−9 W−1,
- a zero-dispersion wavelength of the first optical fiber is not at a wavelength of the signal light nor at a wavelength of the pumping light, and
- a cut-off wavelength of the first optical fiber is equal to or less than the wavelength of the pumping light,
- the first optical fiber includes,
- a glass part including,
- a first core,
- a second core surrounding the first core, and
- a cladding surrounding the second core;
- and
- a coating surrounding the glass part,
- the first core has a relative refractive index difference to the cladding of Δ1 and the second core has a relative refractive index difference to the cladding of Δ2 where Δ1 is 2.2 to 2.8%, and Δ2 is −0.55 to −0.23%, and
- a ratio of a diameter of the first core to a diameter of the second core is 0.33 or more and 0.48 or less.
16 more elements
An optical communication system that transmits a signal light, the optical communication system comprising:
- a Raman amplifier that Raman amplifies the signal light, the Raman amplifier including
- an input unit to which the signal light is input;
- an output unit from which amplified signal light is output;
- an optical fiber for Raman amplifying the signal light with a pumping light provided in at least a part between the input unit and the output unit;
- and
- a pumping light source that supplies a pumping light to the optical fiber, wherein
- a chromatic dispersion of the optical fiber at a wavelength of 1,550 nanometers is in a range between −70 ps/nm/km and −30 ps/nm/km,
- a Raman gain efficiency of the optical fiber with a pumping light of 1,450 nanometers is equal to or more than 5 (W×km)−1,
- a nonlinear coefficient of the optical fiber at the wavelength of 1,550 nanometers is equal to or less than 5.0×10−9W−1,
- a zero-dispersion wavelength of the optical fiber is not at a wavelength of the signal light nor at a wavelength of the pumping light,
- a cut-off wavelength of the optical fiber is equal to or less than the wavelength of the pumping light,
- the optical fiber includes,
- a glass part including,
- a first core,
- a second core surrounding the first core, and
- a cladding surrounding the second core;
- and
- a coating surrounding the glass part,
- the first core has a relative refractive index difference to the cladding of Δ1 and the second core has a relative refractive index difference to the cladding of Δ2 where Δ1 is 2.2 to 2.8%, and Δ2 is −0.55 to −0.23%, and
- a ratio of a diameter of the first core to a diameter of the second core is 0.33 or more and 0.48 or less.
17 more elements
An optical communication system that transmits a signal light, the optical communication system comprising:
- a Raman amplifier that Raman amplifies the signal light, the Raman amplifier including
- an input unit to which the signal light is input;
- an output unit from which amplified signal light is output;
- an optical fiber for Raman amplifying the signal light with a pumping light provided in at least a part between the input unit and the output unit;
- and
- a pumping light source that supplies a pumping light to the optical fiber, wherein
- a chromatic dispersion of the optical fiber in the signal light is equal to or less than −7.39×Pout/S [ps/nm/km], where Pout [mW/ch] is a signal power at an output end of the optical fiber, and S is a wavelength interval between adjacent wavelength-division-multiplexed signals,
- a Raman gain efficiency of the optical fiber with a pumping light of 1,450 nanometers is equal to or more than 5 (W×km)−1,
- a nonlinear coefficient of the optical fiber at the wavelength of 1,550 nanometers is equal to or less than 5.0×10−9 W−1,
- a zero-dispersion wavelength of the optical fiber is not at a wavelength of the signal light nor at a wavelength of the pumping light,
- a cut-off wavelength of the optical fiber is equal to or less than the wavelength of the pumping light,
- a chromatic dispersion of the optical fiber at a wavelength of 1,550 nanometers is in a range between −70 ps/nm/km and −30 ps/nm/km,
- the optical fiber includes,
- a glass part including,
- a first core,
- a second core surrounding the first core, and
- a cladding surrounding the second core;
- and
- a coating surrounding the glass part,
- the first core has a relative refractive index difference to the cladding of Δ1 and the second core has a relative refractive index difference to the cladding of Δ2 where Δ1 is 2.2 to 2.8%, and Δ2 is −0.55 to −0.23%, and
- a ratio of a diameter of the first core to a diameter of the second core is 0.33 or more and 0.48 or less.
18 more elements
Dependencies are inferred from the claim text.