Wavelength division multiplexed optical communication system

• US 6,271,948 B1
• Filed: 05/14/1998
• Issued: 08/07/2001
• Est. Priority Date: 05/16/1997
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Toyohara, Atsushi
• Primary Examiner(s): Chan, Jason
• Assistant Examiner(s): Leung, Christina Y
• Application Number:
  US09/078,574
• Time in Patent Office: 1,181 Days
• Field of Search: 359/341, 359/124, 359/127, 359/133, 359/115
• US Class Current: 398/9
• CPC Class Codes: H04B 10/294 in a multiwavelength system, e.g. gain equalisation
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant

Abstract

It is the object of the invention to provide a small-sized and low-priced WDM optical signal transmission system, in which the transmitting power levels of optical signals are high and equalized. The WDM optical signal transmission system comprises plural light sources of different wavelengths, and the plural optical signals generated by the plural signal light sources are classified into several groups. The optical signals belonging to the same group are multiplexed by the same couplers and amplified by the same optical fiber amplifiers. The outputs of the optical fiber amplifiers are multiplexed by another coupler and supplied to an optical transmission line. in the modified WDM optical signal transmission system, optical band pass filters are respectively allocated between the output ports of the optical fiber amplifiers and the coupler, the outport of which is connected with the input end of the optical transmission line.

Claims

1. A wavelength division multiplexing (WDM) optical communication system comprising:

plural signal light sources for respectively generating optical signals with different wavelengths,

wherein said optical signals are classified into plural groups of said optical signals, wherein said plural groups are classified according to optical signals having nearly a same power level,

plural first stage optical couplers for respectively multiplexing said plural groups of said plural optical signals,

plural optical amplifiers for respectively amplifying outputs of said plural first stage optical couplers, and

a second stage optical coupler for multiplexing outputs of said plural optical amplifiers,

plural optical amplifiers for respectively amplifying outputs of said plural first stage optical couplers, and

a second stage optical coupler for multiplexing outputs of said plural optical amplifiers.

2. A WDM optical communication system according to claim 1 further comprising:

plural optical band pass filter for respectively transmitting outputs of said plural optical amplifiers, which are respectively allocated between said plural optical amplifiers and said second stage optical coupler.

3. A WDM optical communication system according to claim 1, wherein:

said optical amplifiers are respectively optical fiber amplifiers, cores of which are doped with rare earth metal.

4. A WDM optical communication system comprising:

plural signal light sources for respectively generating optical signals with different wavelengths,

wherein, said optical signals are classified into one or more individual optical signals and one or more groups of plural optical signals, wherein each of said groups comprise optical signals having nearly a same power level,

one or more first stage optical couplers for respectively multiplexing said one or groups of said plural optical signals, plural optical amplifiers for respectively amplifying said one or more individual optical signals and outputs of said one or more first stage optical couplers, and a second stage optical couplers for multiplexing outputs of said plural optical amplifiers.

5. A WDM optical communication system according to claim 4 further comprising:

plural optical band pass filter for respectively transmitting outputs of said plural optical amplifiers, which are respectively allocated between said plural optical amplifiers and said second stage optical coupler.

6. A WDN optical communication system according to claim 4, wherein:

said plural optical amplifiers are respectively optical fiber amplifiers, cores of which are doped with rare earth metal.