Optical add/drop node and method

• US 20030223682A1
• Filed: 05/30/2002
• Published: 12/04/2003
• Est. Priority Date: 05/30/2002
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Network Communications Incorporated (Fujitsu Limited)
• Inventors: Takeguchi, Koji, Kinoshita, Susumu
• Granted Patent: US 6,842,562 B2
• Time in Patent Office: Days
• US Class Current: 385/24
• 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 14/021 Reconfigurable arrangements, e.g. reconfigurable optical add/drop multiplexers [ROADM] or tunable optical add/drop multiplexers [TOADM]
• 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 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0241 Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/0287 Protection in WDM systems
• CPC Class Codes: H04J 14/0289 Optical multiplex section protection
• CPC Class Codes: H04J 14/0291 Shared protection at the optical multiplex section (1:1, n:m)
• CPC Class Codes: H04J 14/0294 Dedicated protection at the optical channel (1+1)
• 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

An add/drop node (OADN) comprises a network optical fiber carrying a signal on an optical network. A network drop splitter is coupled to the network optical fiber and to stages of drop splitters, the stages of drop splitters being operable to passively split an optical signal from the network drop splitter into multiple copies of the signal. The OADN further comprises at least one filter operable to receive at least a copy of the signal from at least one drop splitter to create a filtered copy, and further comprises at least one broadband receiver operable to receive the filtered copy from the filter.

Claims

1. An add/drop node for an optical network, comprising:

a network drop splitter operable to be coupled to a network optical fiber and to stages of drop splitters, the stages of drop splitters operable to passively split an optical signal from the network drop splitter into multiple copies of the signal; and

a plurality of filters, each of the filters operable to filter at least a copy of the signal from at least one drop splitter so as to pass a specific traffic channel to a coupled receiver.

2. The add/drop node of claim 1, wherein the filter comprises a tunable filter.

3. The add/drop node of claim 1, wherein the receiver comprises a broadband receiver.

4. The add/drop node of claim 1, further comprising a network add splitter coupled to the network optical fiber and to stages of add splitters, the stages of add splitters operable to passively combine optical signals from the plurality of transmitters onto the network optical fiber via the network add splitter.

5. The add/drop node of claim 4, further comprising a plurality of amplifiers operable to amplify the signal from the transponders.

6. The add/drop node of claim 5, further comprising at least one filter operable to reduce the noise of the amplifier.

7. The add/drop node of claim 1, further comprising a channel reuse module operable to be coupled to the network optical fiber and further operable to selectively terminate portions of the signal on the network optical fiber.

8. The add/drop node of claim 7, wherein the channel reuse module comprises a demultiplexer, a plurality of optical switches operable to terminate selected wavelengths from the signal, and a multiplexer.

9. The add/drop node of claim 7, wherein the channel reuse module comprises a plurality of band pass filters operable to terminate selected grouping paths from the signal on the network optical fiber.

10. The add/drop node of claim 7, wherein the channel reuse module comprises:

a circulator;

a demultiplexer;

a plurality of tunable filters;

a plurality of mirrors; and

a multiplexer,

operable to terminate selected wavelengths from the signal on the network optical fiber.

11. The add/drop node of claim 1, further comprising a redundant tunable filter operable to pass a specific traffic channel to a broadband receiver in the event of a failure of the specific traffic channel to pass to its normally intended receiver.

13. The optical network of claim 10, wherein the add/drop node further comprises a network add splitter coupled to the network optical fiber and to stages of add splitters, the stages of add splitters operable to passively combine optical signals from the plurality of transmitters onto the network optical fiber via the network add splitter.

12. An optical network, comprising:

a network optical fiber carrying a signal on the optical network; and

at least one add/drop node, the add/drop node comprising;

a network drop splitter coupled operable be coupled to a network optical fiber and to stages of drop splitters, the stages of drop splitters operable to passively split an optical signal from the network drop splitter into multiple copies of the signal; and

a plurality of filters, each of the filters operable to receive at least a copy of the signal from at least one drop splitter and to filter the copy to pass a specific traffic channel to a coupled broadband receiver.

14. A method of managing signals on an optical network, comprising:

transmitting a plurality of optical signals from a plurality of transmitters;

passively combining the plurality optical signals into an add signal;

passively combining the add signal to a passthrough signal to generate an egress signal for transport on an optical network;

passively splitting ingress optical signal from the network into a transport signal and a drop signal;

passively splitting the drop signal into multiple copies of the drop signal;

filtering each of the multiple drop signals to pass from each of the multiple drop signals a selected drop channel;

receiving the selected drop channels at receivers; and

passing at least selected channels of the transport signal as the passthrough signal.

15. The method of claim 14, further comprising amplifying at least one of the optical signals transmitted from the plurality of transponders.

16. The method of claim 14, wherein the passing of at least selected channels of the transport signal comprises filtering the signal.

17. The method of claim 14, wherein the passing of at least selected channels of the transport signal comprises terminating the signal with an optical switch.

18. The method of claim 14, wherein the passing of at least a selected channels of the transport signal comprises terminating selected grouping paths.

19. An add/drop node for an optical network, comprising:

a transport element operable to passively drop local drop traffic from an ingress signal to a distributor and to passively add local add traffic from a combiner to a passthrough signal to generate an egress signal; and

a channel reuse module operable to selectively terminate one or more channels of the ingress signal to generate the passthrough signal.

20. The add/drop node of claim 19, wherein the channel reuse module comprises a demultiplexer, a plurality of optical switches operable to terminate selected wavelengths from the signal, and a multiplexer.

21. The add/drop node of claim 19, wherein the channel reuse module comprises a plurality of band path filters operable to terminate selected grouping paths from the signal on the network optical fiber.

22. The add/drop node of claim 19, wherein the channel reuse module comprises:

a circulator;

a demultiplexer;

a plurality of tunable filters;

a plurality of mirrors; and

a multiplexer,

operable to terminate selected wavelengths from the signal on the network optical fiber.

23. An add/drop node for an optical network, comprising:

means for transmitting a plurality of optical signals;

means for passively combining the plurality optical signals into an add signal;

means for passively combining the add signal to a passthrough signal to generate an egress signal for transport on an optical network;

means for passively splitting ingress optical signal from the network into a transport signal and a drop signal;

means for passively splitting the drop signal into multiple copies of the drop signal;

means for filtering each of the multiple drop signals to pass from each of the multiple drop signals a selected drop channel;

means for receiving the selected drop channels; and

means for passing at least selected channels of the transport signal as the passthrough signal.

24. The add/drop node of claim 23, further comprising means for amplifying at least one of the optical signals transmitted from the plurality of transponders.

25. The method of claim 23, wherein the means for passing the at least selected channels of the transport signal comprises a filter.

26. The method of claim 23, wherein the means for passing the at least selected channels of the transport signal comprises an optical switch.

27. An add/drop node for an optical network, comprising:

a network drop splitter operable to passively drop from the optical network a combined signal, the combined signal comprising a plurality of traffic channels;

a passive distributor coupled to the network drop splitter, the passive distributor comprising a plurality of stages of drop splitters, each of the stages operable to passively split each of one or more copies of the combined signal provided to the stage into a plurality of copies of the combined optical signal; and

the passive distributor further comprising a plurality of filters coupled to the stages of drop splitters, each filter operable to filter a copy of the combined signal so as to pass a specific traffic channel to a coupled receiver.

28. The add/drop node of claim 27, further comprising a channel reuse module operable to be coupled to the network optical fiber and further operable to selectively terminate portions of the signal on the network optical fiber.

29. The add/drop node of claim 28, wherein the channel reuse module comprises a demultiplexer, a plurality of optical switches operable to terminate selected wavelengths from the signal, and a multiplexer.

30. The add/drop node of claim 28, wherein the channel reuse module comprises a plurality of band path filters operable to terminate selected grouping paths from the signal on the network optical fiber.

31. The add/drop node of claim 28, wherein the channel reuse module comprises:

a circulator;

a demultiplexer;

a plurality of tunable filters;

a plurality of mirrors; and

a multiplexer,

operable to terminate selected wavelengths from the signal on the network optical fiber.