WDM ring network for flexible connections

• US 7,218,805 B2
• Filed: 07/12/2002
• Issued: 05/15/2007
• Est. Priority Date: 07/13/2001
• Status: Expired due to Term

• Current Assignee: Transmode AB (Infinera Corp.)
• Original Assignee: Transmode AB (Infinera Corp.)
• Inventors: Oberg, Magnus
• Primary Examiner(s): Font; Frank G.
• Assistant Examiner(s): Mooney; Michael P.
• Application Number:
  US10/483,390
• Publication Number:
  US 20040175071A1
• Time in Patent Office: 1,768 Days
• Field of Search: 385/24, 385 16- 17, 398/71, 398/79, 398/82, 398/83
• 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 14/021 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 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/029 Dedicated protection at the optical multiplex section (1+1)
• CPC Class Codes: H04J 14/0294 Dedicated protection at the optical channel (1+1)
• CPC Class Codes: H04J 14/0297 Optical equipment protection
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 11/0067 Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
• CPC Class Codes: H04Q 2011/0022 using fibre gratings
• CPC Class Codes: H04Q 2011/0035 using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical
• CPC Class Codes: H04Q 2011/0047 Broadcast; Multicast
• CPC Class Codes: H04Q 2011/0092 Ring

Abstract

A broadcast and select ring network for optical WDM communication includes two parallel fiber rings (1a, 1b) carrying traffic in opposite directions between nodes (3; A, B, C, D). The nodes comprise on their receive side selecting means such as a cross connect device (21) or similar means allowing a flexible selection of the wavelength channels which are to be received by each node. Thereby, any WDM channel in the rings can be selected and received in the nodes. For example, all nodes can receive signals in the same channel for e.g. set up or reconfiguration purposes. Furthermore, the number of receivers in a node can be small but still all channels can be received. The number of transmitters in each a node can also be small since every transmitter can reach every receiver.

Claims

1. An optical WDM network for flexible connections comprising:

at least one fiber ring path for carrying light signals, and

nodes connected in said at least one ring path and having transmit and receive sides arranged to transmit and receive respectively light signals carrying information in distinct wavelength channels,

receiver units and transmitter units comprised in the nodes, at least one of the nodes comprising;

at least one add filter connected in the fiber ring path for adding light signals from the transmitter units of said at least one of the nodes to the light signals in said at least one fiber ring path,

an optical power splitter connected in said at least one fiber ring path, the optical power splitter tapping off a portion of the power of signals propagating in said at least one fiber ring path, the portion containing light signals in all wavelength channels incoming to said at least one of the nodes,

a demultiplexer connected to receive the tapped-off portion from the optical power splitter in said at least one of the nodes and separating the signals of the wavelength channels comprised in said tapped-off portion from each other, and

a selector connected to receive the separated signals of the wavelength channels from the demultiplexer and connected to the receiver units of said least one of the nodes for switching signals in selected ones of the wavelength channels to the receiver units so that each of the receiver units of said at least one of the nodes can be selected to receive signals of any one of all of the wavelength channels.

2. An optical WDM network according to claim 1, wherein the add filter is a band add filter.

3. An optical WDM network according to claim 2, wherein the add filter is a band add filter for adding lights signals in at least two adjacent wavelength channels.

4. An optical WDM network according to claim 1, wherein the selector is an optical crossconnect unit.

5. An optical WDM network according to claim 1, wherein two parallel fiber ring paths carry signals in opposite directions, each one of the nodes being connected to the two parallel fiber ring paths and said at least one of the nodes comprising two demultiplexers, one demultiplexer for each of the two parallel fiber ring paths, the selector of said at least one of the nodes comprising a single optical crossconnect unit connected to receive signals from the two demultiplexers.

6. An optical WDM network according to claim 1, wherein two parallel fiber ring paths, one first fiber ring path and one second fiber ring path, carry signals in opposite directions.

7. An optical WDM network according to claim 6, wherein said at least one of the nodes further comprises:

optical power splitters connected in the two parallel fiber ring paths, one of the optical power splitters connected in the first fiber ring path and a different one of the optical power splitters connected in the second fiber ring path, each of the optical power splitters tapping off a portion of the power of signals propagating in a respective one of the two parallel fiber ring paths, and

demultiplexers connected to receive said tapped-off portions from the optical power splitters, the demultiplexers separating the signals of the wavelength channels comprised in said tapped-off portions from each other and providing the separated signals to the selector.

8. An optical WDM network according to claim 7, wherein the selector comprises a single optical crossconnect unit connected to receive the separated signals from the demultiplexers.

9. An optical WDM network according to claim 7, wherein said at least one of the nodes further comprises:

optical switches connected to receive signals from the demultiplexers, a first input terminal of each of the optical switches connected to receive signals derived prom the first fiber ring path and a second input terminal of each of the optical switches connected to receive signals derived from the second fiber ring path, each of the optical switches transferring signals from one of two input terminals to a single output terminal connected to one of the receiving units of said at least one of the nodes.

10. An optical WDM network according to claim 7, wherein at least one of the receiver units of said at least one of the nodes comprises two receiver elements connected to receive signals from the demultiplexers, a first receiver element connected to receive signals derived from the first fiber ring path and a second receiver element connected to receive signals derived from the second fiber ring path, the receiver elements of said at least one of the receiver units connected to each other so that only one of the two receiver elements can be active at a time, receiving signals from a respective one of the demultiplexers.

11. An optical WDM network according to claim 1, wherein the selector of said at least one of the nodes comprises an optical power splitter and tunable band pass filters, the optical power splitter splitting incoming signal power into a number of substantially equal fractions, each fraction fed to one of the tunable band pass filters that have output terminals connected to the receiver units of said at least one of the nodes.

12. An optical WDM network according to claim 1, wherein the selector of said at least one of the nodes comprises tunable band pass filters connected in series with each other, the tunable band pass filters having output terminals connected to the receiver units of said at least one of the nodes.

13. An optical WDM network according to claim 12, wherein said at least one of the nodes further comprises an optical fiber line extending from an output terminal of the optical power splitter of said at least one of the nodes, the tunable band pass filters connected in series with each other in the optical fiber line.

14. An optical WDM network according to claim 12, wherein the tunable band pass filters are connected in said at least one fiber ring path.

15. An optical WDM network according to claim 6, wherein said at least one of the nodes further comprises two receiver units for each of client equipments in said at least one of the nodes, the two receiver units receiving signals from different ones of the two parallel fiber ring paths.

16. An optical WDM network according to claim 15, wherein said two receiver units for each of client equipments are controllable to be in on and off positions so that when one of the two receiver units is on, the other one of the two receiver units is off and vice versa.

17. An optical WDM network according to claim 1, wherein the number of the receiver units in said at least one of the nodes is smaller than the number of the wavelength channels.

18. An optical WDM network for flexible connections comprising:

at least one fiber ring path for carrying light signals, and

nodes connected in the ring path, and having transmit and receive sides arranged to transmit and receive respectively light signals carrying information in distinct wavelength channels,

receiver units comprised in the, nodes,

at least one of nodes further comprises a selector connected to the receiver units of said at least one of the nodes for switching signals in selected ones of the wavelength channels to the receiver units of said at least one of the nodes so that each of the receiver units of said at least one of the nodes can be selected to receive signals of any one of the wavelength channels, the selector comprising tunable band pass filters connected in series with each other, the tunable band pass filters having output terminals connected to the receiver units of said at least one of the nodes.

19. An optical WDM network according to claim 18, wherein parallel fiber ring paths, a first fiber ring path and a second fiber ring path, carry signals in opposite directions.

20. An optical WDM network according to claim 19, wherein said at least one of the nodes further comprises two receiver units for each of client equipments in said at least one of the nodes, the two receiver units receiving signals from different ones of the two parallel fiber ring paths.

21. An optical WDM network according to claim 20, wherein said two receiver units for each of client equipments are controllable to be in on and off positions so that when one of the two receiver units is on, the other one of the two receiver units is off and vice versa.

22. An optical WDM network according to claim 18, wherein the number of the receiver units in said at least one of the nodes is smaller than the number of the wavelength channels.

23. A node for an optical WDM network allowing flexible connections, the network comprising at least one fiber ring path for carrying light signals, the node being connectable in said at least one ring path, the node having transmit and receive sides arranged to transmit and receive respectively light signals carrying information in distinct wavelength channels, the transmit side comprising at least one transmitter unit and the receive side comprising at least one receiver unit, the node further comprising:

at least one add filter connectable in said at least one fiber ring path for adding light signals from said at least one transmitter unit to light signals in the fiber ring path when the node is connected in an optical WDM network,

an optical power splitter connectable in said at least one fiber ring path for tapping off a portion of power of signals propagating in the at least one fiber ring path, said tapped-off portion containing light signals in all wavelength channels incoming to the node when connected in an optical WDM network,

a demultiplexer connected to receive the tapped-off portion from the optical power splitter and separating the signals of the wavelength channels comprised in said tapped-off portion from each other, and

a selector connected to receive the separated signals of the wavelength channels from the demultiplexer and connected to said at least one receiver unit for switching signals in one selected among all of the wavelength channels to said at least one receiver unit.

24. A node according to claim 23, wherein the add filter is a band add filter.

25. A node according to claim 24, wherein the add filter is a band add filter for adding lights signals in at least two adjacent wavelength channels.

26. A node according to claim 23, further comprising at least two receiver units, the selector connected to all of said at least two receiver units for switching signals in selected ones of the wavelength channels to the receiver units so that each of said at least two receiver units can be selected to receive signals of any one of all of the wavelength channels.

27. A node for an optical WDM network allowing flexible connections, the network comprising at least one fiber ring path for carrying light signals, the node being connectable in said at least one ring path, the node having transmit and receive sides arranged to transmit and receive respectively light signals carrying information in distinct wavelength channels, the receive side comprising at least two receiver units, a selector connected to said at least two receiver units for switching signals in selected ones of the wavelength channels to said at least two receiver units so that each of said at least two receiver units can be selected to receive signals of any one of the wavelength channels, the selector comprising tunable band pass filters connected in series with each other, the tunable band pass filters having output terminals connected to said at least two receiver units.