Raman Amplifier And Optical Communication System

• US 20080013161A1
• Filed: 08/30/2004
• Published: 01/17/2008
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Independent Administrative Institution, Japan Agency For Marine-Earth Science And Technology, Rakuten Group, Inc.
• Original Assignee: Independent Administrative Institution, Japan Agency For Marine-Earth Science And Technology, Mitsubishi Electric Corporation
• Inventors: Shimizu, Katsuhiro, Mikada, Hitoshi, Asakawa, Ken'ichi, Tokura, Toshiyuki, Fujieda, Tasuku, Kawaguchi, Katsuyoshi
• Granted Patent: US 7,768,698 B2
• Time in Patent Office: Days
• US Class Current: 359/334
• CPC Class Codes: H01S 3/06725 Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
• CPC Class Codes: H01S 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/094076 Pulsed or modulated pumping H01S3/1024 takes precedence
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/1001 by controlling the optical pumping
• CPC Class Codes: H01S 3/302 in an optical fibre
• CPC Class Codes: H04B 10/2916 using Raman or Brillouin amplifiers

Abstract

A Raman amplifier includes a pumping light source, an optical coupler, and a Raman amplifier medium. The pumping light source outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz. The optical coupler couples the pumping light with a carrier light. The Raman amplification medium is pumped by the pumping light to amplify the carrier light. The Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.

Claims

1-9. -9. (canceled)

10. A Raman amplifier comprising:

a pumping light source that outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz;

an optical coupler that couples the pumping light with a carrier light; and

a Raman amplification medium that is pumped by the pumping light to amplify the carrier light, wherein

the Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.

11. The Raman amplifier according to claim 10, wherein

the Raman amplification medium is an optical fiber, and

an absolute value of a dispersion value of the optical fiber is equal to or less than 1/(a modulation frequency of the pumping light source×

a length of the optical fiber×

a difference between wavelengths of the pumping light and the carrier light)[ps/nm/km].

12. The Raman amplifier according to claim 10, wherein

the Raman amplification medium is an optical fiber, and

a Raman gain efficiency of the optical fiber is equal to or higher than 5/W/km.

13. The Raman amplifier according to claim 11, wherein

a Raman gain efficiency of the optical fiber is equal to or higher than 5/W/km.

14. The Raman amplifier according to claim 10, wherein

the Raman amplification medium is an optical fiber,

a wavelength of the pumping light is within a range of 1.4 micrometers to 1.5 micrometers, and

a wavelength of the carrier light is within a range of 1.5 micrometers to 1.6 micrometers.

15. The Raman amplifier according to claim 10, wherein

the Raman amplification medium includes a plurality of first fibers having positive dispersion and a plurality of second fibers having negative dispersion connected alternately in series.

16. A Raman amplifier comprising:

a plurality of Raman amplifier units that are connected in a cascaded manner, wherein

each of the Raman amplifier units includes

a pumping light source that outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz;

an optical coupler that couples the pumping light with a carrier light; and

a Raman amplification medium that is pumped by the pumping light to amplify the carrier light, and

the Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.

17. An optical communication system comprising:

a transmitter that transmits a carrier light;

a Raman amplifier that receives the carrier light, and outputs a modulated carrier light; and

a receiver that receives the modulated carrier light, wherein

the Raman amplifier includes

a pumping light source that outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz;

an optical coupler that couples the pumping light with the carrier light; and

a Raman amplification medium that is pumped by the pumping light to amplify the carrier light,

the Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light, and the transmitter, the Raman amplifier, and the receiver are connected with an optical fiber cable.

18. The optical communication system according to claim 17, further comprising an observation device that generates an observation signal, and outputs the observation signal to the Raman amplifier, wherein

the Raman amplifier modulates the pumping light based on the observation signal, to output the modulated carrier light.