Optical transmission system

• US 20040246566A1
• Filed: 03/04/2004
• Published: 12/09/2004
• Est. Priority Date: 03/04/2003
• Status: Abandoned Application

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Kobayashi, Junko, Tanaka, Masato, Okuno, Toshiaki, Miyamoto, Toshiyuki, Nishimura, Masayuki, Shigematsu, Masayuki
• Application Number:
  US10/792,034
• Publication Number:
  US 20040246566A1
• Time in Patent Office: Days
• US Class Current: 359/334
• CPC Class Codes: H01S 3/302 in an optical fibre
• CPC Class Codes: H04B 10/2916 using Raman or Brillouin amplifiers

Abstract

The present invention relates to an optical transmission system having a structure to enable signal transmission while maintaining superior transmission characteristics over a broader wavelength band. Signal light outputted from a signal light source has a positive chirp, and propagates through a transmission line fiber to an optical receiver, after being Raman-amplified by a lumped Raman amplifier. The lumped Raman amplifier includes, as a Raman amplification fiber, a high-nonlinearity fiber having a negative chromatic dispersion at a wavelength of the signal light and intentionally generating a self-phase modulation therein. The positive chirp of the signal light propagating through the high-nonlinearity fiber is effectively compensated by both of the negative chromatic dispersion and the self-phase modulation generated in the high-nonlinearity fiber.

Claims

1. An optical transmission system comprising:

a signal light source outputting signal light with a positive chirp;

an optical fiber transmission line through which the signal light propagates; and

a lumped Raman amplifier provided between said signal light source and said optical fiber transmission line, and Raman-amplifying the signal light outputted from said signal light source, said lumped Raman amplifier including a high-nonlinearity fiber having a negative chromatic dispersion at a wavelength of the signal light and a nonlinear coefficient (2 π

/λ

)·

(n₂/A_eff) of 6.9 (1/W/km) or more which is defined by a nonlinear refractive index n₂ and an effective area A_eff at a wavelength of λ

.

3. An optical transmission system according to claim 1, wherein the nonlinear coefficient (2 π

/λ

)·

(n₂/A_eff) of said high-nonlinearity fiber is 12.2 (1/W/km) or more.

4. An optical transmission system according to claim 1, wherein said high-nonlinearity fiber has a transmission loss of 0.7 dB or less at a wavelength of 1500 nm.

5. An optical transmission system according to claim 1, wherein said high-nonlinearity fiber has a transmission loss whose increase, to which OH-absorption near a wavelength of 1390 nm contributes, is 0.5 dB/km or less.

6. An optical transmission system according to claim 1, wherein said high-nonlinearity fiber has a chromatic dispersion of −

20 ps/nm/km or less at the wavelength of the signal light.

7. An optical transmission system according to claim 1, wherein the signal light includes a plurality of signal channels having a wavelength spacing of 10 nm or more, and said high-nonlinearity fiber ha a chromatic dispersion of −

10 ps/nm/km or less at the wavelength of the signal light.

2. An optical transmission system according to claim 2, wherein a phase shift amount Φ

_LRA of the signal light in said high-nonlinearity fiber is ½

or more of a phase shift amount Φ

_T of the signal light in said optical fiber transmission line.