Combining and distributing amplifiers for optical network and method

• US 7,075,712 B2
• Filed: 05/30/2002
• Issued: 07/11/2006
• Est. Priority Date: 05/30/2002
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tian, Cechan, Kinoshita, Susumu, Pecqueur, Remi
• Primary Examiner(s): Hughes, Deandra M.
• Application Number:
  US10/159,499
• Publication Number:
  US 20030223104A1
• Time in Patent Office: 1,503 Days
• Field of Search: 359/349, 398/66
• US Class Current: 359/349
• CPC Class Codes: H04B 10/27 Arrangements for networking
• CPC Class Codes: H04B 10/275 Ring-type networks
• CPC Class Codes: H04J 14/0204 Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping
• CPC Class Codes: H04J 14/0205 Select and combine arrangements, e.g. with an optical combiner at the output after adding or dropping
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• CPC Class Codes: H04J 14/0209 Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements
• CPC Class Codes: H04J 14/0219 Modular or upgradable architectures
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/02216 by gain equalization
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0228 Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths
• CPC Class Codes: H04J 14/0238 Wavelength allocation for communications one-to-many, e.g. multicasting wavelengths
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0291 Shared protection at the optical multiplex section (1:1, n:m)
• CPC Class Codes: H04J 14/0295 Shared protection at the optical channel (1:1, n:m)
• CPC Class Codes: H04J 14/0297 Optical equipment protection

Abstract

A system for distributing optical signals comprises a plurality of optical splitter stages. The optical splitter stages are each operable to passively split each of one or more optical signals provided to the stage into a plurality of optical signals. At least one of the optional splitter stages comprises an amplification stage, with the amplification stage including a plurality of gain media. The gain media are each operable to amplify an optical signal with pump power.

Claims

1. An optical node for distributing optical signals, comprising:

a plurality of optical splitter stages within the optical node, the optical splitter stages each operable to passively split each of one or more optical signals provided to the stage into a plurality of optical signals having substantially identical content, the plurality of optical stages comprising;

a first optical splitter stage including an optical splitter operable to split a first stage ingress signal into a plurality of first stage egress signals; and

a second optical splitter stage including a different optical splitter for each of the first stage egress signals, each second-stage optical splitter operable to split the associated first stage egress signal into a plurality of second stage egress signals;

the first and second optical splitter stages each comprising an amplification stage, the amplification stage including a plurality of gain media;

the gain media each operable to amplify an associated egress signal from the associated optical splitter stage with pump power; and

wherein the optical splitter stages comprise a plurality of branches, and further comprising couplers connecting at least two of the branches to reduce an imbalance of signal power of the branches.

2. The system of claim 1, wherein the gain media comprise erbium-doped optical fibers.

3. The system of claim 1, wherein the gain media comprise doped optical fibers.

4. The system of claim 1, wherein the gain media comprise erbium-doped waveguides.

5. The system of claim 1, wherein the amplification stages includes a pump splitter operable to feed pump power into the amplification stage.

6. The system of claim 5, wherein the amplification stage is downstream of a stage including a pump splitter operable to feed pump power into the amplification stage.

7. The system of claim 1, the plurality of optical splitter stages each comprising one or more optical splitters, the optical splitters operable to passively split a provided optical signal into a plurality of optical signals.

8. The system of claim 7, further comprising:

a plurality of the optical splitters comprising pump combiners; and

the pump combiners each operable to feed pump power into an optical splitter stage, including the pump combiner.

9. The system of claim 7, wherein the optical splitters each comprise a 2:

2 coupler.

10. The system of claim 7, wherein the optical splitters each comprise a 3:

3 coupler.

11. The system of claim 1, further comprising a preamplifier, the preamplifier including a pump coupler operable to feed pump power into the preamplifier, a gain medium operable to amplify a preamplifier ingress signal with the pump power and a gain flattener operable to limit gain in the preamplifier.

12. The system of claim 11, further comprising an isolator coupled between a transmission link and the preamplifier.

13. The system of claim 1, further comprising a controller operable to control gain of optical signals in a distribution system.

14. The system of claim 13, the controller operable to limit a power of optical signals at specified points in the distribution system to less than about 17 dBm.

15. The system of claim 13, wherein the controller comprises an automatic gain controller (AGC), the AGC operable to monitor a power of ingress and egress optical signals of the distribution system and to control pump power based on the power of the ingress and egress optical signals.

16. The system of claim 14, wherein the specified points comprise expansion ports of the distribution system.

17. The system of claim 1, wherein the amplification stage is operable to substantially eliminate a power loss of the signal being passively split.

18. A method for distributing an optical signal at an optical node, comprising:

passively splitting, at the optical node, an ingress optical signal comprising one or more channels into a plurality of egress optical signals each having substantially identical content as the ingress optical signal and each comprising the one or more channels, wherein passively splitting the ingress optical signal comprises;

using a first optical splitter stage including an optical splitter to split the ingress signal into a plurality of first stage egress signals; and

using a second optical splitter stage, including a different optical splitter for each of the first stage egress signals, to split each of the first stage egress signals into a plurality of second stage egress signals;

amplifying, at the optical node, each of the first stage and second stage egress optical signals with pump power; and

reducing an imbalance of signal power resulting from the optical signal being passively split.

19. The method of claim 18, wherein the egress optical signals are each amplified in a gain medium comprising a doped fiber.

20. The method of claim 18, wherein the egress optical signals are each amplified in a gain medium comprising an erbium-doped fiber.

21. The method of claim 18, wherein the egress optical signals are each amplified in a gain medium comprising an erbium-doped waveguide.

22. The method of claim 18, wherein the optical signal comprises a single channel, further comprising providing each of the egress optical signals to a subscriber of the channel.

23. The method of claim 18, further comprising preamplifying the ingress optical signal prior to passively splitting the ingress optical signal.

24. The method of claim 18, further comprising controlling amplification gain.

25. The method of claim 18, further comprising:

monitoring a power level of the ingress optical signal and an egress optical signal;

determining a gain based on the power levels of the ingress and egress optical signals; and

controlling pump power based on the determined gain.

26. The method of claim 18, further comprising limiting the power of the egress optical signals to an eye-safe level.

27. The method of claim 18, wherein amplifying each of the egress optical signals substantially eliminates a power loss of the egress signals relative to the ingress signal.

28. An optical node for distributing an optical signal, comprising:

means for passively splitting, at the optical node, an ingress optical signal comprising one or more channels into a plurality of egress optical signals each having substantially identical content as the ingress optical signal and each comprising the one or more channels, wherein the means for passively splitting the ingress optical signal comprises;

a first optical splitter stage means operable to split the ingress signal into a plurality of first stage egress signals; and

a second optical splitter stage means operable to split each of the first stage egress signals into a plurality of second stage egress signals;

means for amplifying, at the optical node, each of the first stage and second stage egress optical signals with pump; and

means for reducing an imbalance of signal power resulting from the optical signal being passively split.

29. The system of claim 28, wherein the egress optical signals are each amplified in a gain medium comprising a doped fiber.

30. The system of claim 28, wherein the egress optical signals are each amplified in a gain medium comprising an erbium-doped fiber.

31. The system of claim 28, wherein the egress optical signals are each amplified in a gain medium comprising an erbium-doped waveguide.

32. The system of claim 28, wherein the optical signal comprises a single channel, further comprising providing each of the egress optical signals to a subscriber of the channel.

33. The system of claim 28, further comprising means for preamplifying the ingress optical signal prior to passively splitting the ingress optical signal.

34. The system of claim 28, further comprising means for controlling amplification gain.

35. The system of claim 28, further comprising:

means for monitoring a power level of the ingress optical signal and an egress optical signal;

means for determining a gain based on the power levels of the ingress and egress optical signals; and

means for controlling pump power based on the determined gain.

36. The system of claim 28, further comprising means for limiting the power of the egress optical signals to an eye-safe level.

37. The system of claim 28, wherein the means for amplifying each of the egress optical signals is operable to substantially eliminate a power loss of the egress signals relative to the ingress signal.