All-optical network with passive wavelength routers

• US 6,735,393 B1
• Filed: 09/22/2000
• Issued: 05/11/2004
• Est. Priority Date: 09/24/1999
• Status: Expired due to Fees

• Current Assignee: Telenor As
• Original Assignee: Telenor As
• Inventors: Zouganeli, Paraskevi
• Primary Examiner(s): Pascal, Leslie
• Assistant Examiner(s): TRAN, DZUNG D
• Application Number:
  US09/667,544
• Time in Patent Office: 1,327 Days
• Field of Search: 398/45, 398/48, 398/49, 398/50, 398/51, 398/57, 398/63, 398/83, 398/84, 398/85, 370/16
• US Class Current: 398/48
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 2011/0018 using tunable transmitters or receivers
• CPC Class Codes: H04Q 2011/0022 using fibre gratings
• CPC Class Codes: H04Q 2011/0032 using static wavelength routers (e.g. arrayed waveguide grating router [AWGR] )
• CPC Class Codes: H04Q 2011/0035 using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical
• CPC Class Codes: H04Q 2011/0088 Signalling aspects
• CPC Class Codes: H04Q 2011/0098 Mesh

Abstract

An optical network, which may be an all-optical network, including passive wavelength routers is described. Methods for implementing such networks as well as different router configurations which may be used in optical networks are also disclosed. The routing functionality in the all-optical network can be done in the optical domain without switching elements at the nodes. This is achieved by routers which are passive and preferably operative to route wavelength bands. A mesh can be used as the network configuration. The optical networks described can be used to facilitate the transmission of higher network protocols, such as internet protocol (IP) packets or ATM-cells, purely in the optical domain.

Claims

1. An optical network comprising:

a plurality of transmitters configured to transmit optical signals;

a plurality of receivers configured to receive said optical signals;

a plurality of nodes connected by optical fibers and comprising passive wavelength routers comprising passive optical components, said passive wavelength routers being configured to;

impose network-wide routing restrictions restricting routing of said optical signals at said nodes to a selection of possible flow-directions within said optical network, said flow-directions being defined by dividing logically a physical fiber infrastructure of said network in at least two layers, wherein at least one selected flow-direction in one layer is distinct from all selected flow-directions in another layer, and

impose wavelength dependent rules for said optical signals; and

a control system configured to control said optical transmitters thereby controlling end-to-end paths of said optical signals through said optical network.

2. The optical network of claim 1, wherein said at least two layers are interconnected at least at one of said nodes.

3. The optical network of claim 1, wherein said control system is configured to control said receivers.

4. The optical network of claim 1, wherein at least one of said passive wavelength routers is configured to route at least one wavelength band that includes a plurality of consecutive wavelength channels.

5. The optical network of claim 1, wherein said nodes are interconnected to form a mesh network.

6. The optical network of claim 5, wherein said mesh network is a regular grid network.

7. The optical network of claim 1, wherein at least one of the transmitters comprises a fixed wavelength laser.

8. The optical network of claim 1, wherein at least one of said transmitters comprises an array of lasers.

9. The optical network of claim 1, wherein at least one of the transmitters comprises a tunable laser.

10. The optical network of claim 1, wherein at least one of said receivers comprises a fixed-wavelength receiver.

11. The optical network of claim 1, wherein at least one of said receivers comprises a tunable wavelength receiver.

12. The optical network of claim 1, wherein at least one of said passive wavelength routers comprises at least one combiner configured to combine a plurality of optical signals that enter from a plurality of input ports before said optical signals are routed to outputs of said passive wavelengths routers.

13. The optical network in claim 1, wherein at least one of said passive wavelength routers comprises a plurality of input ports and a plurality of output ports, and optical signals from each of the input ports are passively routed to different output directions according to a set of predetermined wavelength dependent rules, and wherein at least one combiner combines at least two of said output directions to a single output port.

14. The optical network of claim 1, further comprising a number of switching elements configured to reconfigure at least one of said flow-direction rules.

15. The optical network in claim 1, further comprising a number of switching elements configured to reconfigure at least one of said wavelength dependent rules.

16. The optical network of claim 1, further comprising a number of wavelength conversion elements configured to reconfigure at least one of said flow-direction rules.

17. The optical network of claim 1, further comprising a number of wavelength conversion elements configured to reconfigure at least one of said wavelength dependent rules.

18. The optical network of claim 1, wherein said passive wavelength routers are configured to receive at least one first optical signal at a first input port, receive at least one second optical signal at a second input port, and route said first and second optical signals to a single output port in accordance with said wavelength dependent rules and said flow-direction dependent rules.

19. The optical network of claim 18, wherein optical signals that enter said at least one of said passive wavelength routers from different input ports, have a same wavelength, and wherein said control system controls which input port uses said wavelength.

20. The optical network of claim 1, wherein at least one of said passive routers comprises at least one broadband wavelength filter configured to filter a plurality of consecutive wavelength channels.

21. The optical network of claim 1, wherein said transmitters transmit Internet protocol packets.

22. The optical network of claim 1, wherein said transmitters transmit Asynchronous Transfer Mode cells.

23. The optical network of claim 1, wherein transmission in said optical fibers is unidirectional.

24. The optical network of claim 1, wherein transmission in said optical fibers is bi-directional.

25. The optical network of claim 1, wherein:

at least a number of said nodes are connected to form a plurality of sub-networks; and

said network further comprises a top network configured to interconnect said sub-networks.

26. The optical network of claim 25, wherein the top network is connected to the sub-networks at a number of nodes, a number of said nodes comprising re-configurable optical cross-connects.

27. A method for routing optical signals through an optical network comprising a plurality of nodes with passive wavelength routers, said method comprising the steps of:

transmitting a plurality of optical signals from at least a number of said nodes;

receiving a plurality of optical signals at least at a number of said nodes;

imposing network-wide routing restrictions restricting routing of said optical signals at said nodes to a selection of possible flow-directions within said optical network, said flow-directions being defined by dividing logically a physical fiber infrastructure of said network in at least two layers, wherein at least one selected flow-direction in one layer is distinct from all selected flow-directions in another layer; and

imposing wavelength dependent rules for said optical signals;

wherein end-to-end paths of said optical signals through said optical network are determined by said transmitting step.

28. The method of claim 27, wherein said flow-directions are further defined by interconnecting said at least two layers at least at one of said nodes.

29. The method of claim 27, wherein said end-to-end paths of said optical signals through said optical network are determined by said receiving step.

30. The method of claim 27, further comprising routing at least one wavelength band with said passive routers, wherein said wavelength band includes a plurality of consecutive wavelength channels.

31. The method of claim 27, wherein the transmitting step is performed using at least one fixed wavelength laser.

32. The method of claim 27, wherein the transmitting step is performed using at least one array of lasers.

33. The method of claim 27, wherein the transmitting step is performed using at least one tunable laser.

34. The method of claim 33, wherein the transmitting step is performed by tuning said widely tunable laser.

35. The method of claim 27, wherein said receiving step is performed using fixed wavelength receivers.

36. The method of claim 27, wherein said receiving step is performed using tunable wavelength receivers.

37. The method of claim 27, further comprising the step of reconfiguring said wavelength dependent rules.

38. The method of claim 27, further comprising the step of reconfiguring said flow-direction rules.

39. The method of claim 27, further comprising the steps of:

inputting a plurality of optical signals in a plurality of input ports of said passive wavelength routers; and

directing the optical signals from at least two of said input ports to a same output port of said passive wavelength routers using at least one passive wavelength filter,

wherein said directing of said optical signals is performed in accordance with said wavelength dependent rules and said flow-direction dependent rules.

40. The method of claim 39, wherein at least two of said optical signals that enter said passive wavelength routers from different input ports have a same wavelength, and wherein the method further comprises a step of controlling with a control system which of said at least two optical signals is transmitted in the network .

41. The method of claim 39, wherein the directing step comprises reflecting a wavelength band with said passive wavelength filter, wherein said reflected wavelength band includes a plurality of consecutive wavelengths channels.

42. An optical router for routing optical signals in an optical network, comprising:

at least one passive wavelength filter configured to;

impose network-wide routing restrictions restricting routing of said optical signals to a selection of possible flow-directions within said optical network, said flow-directions being defined by dividing logically a physical fiber infrastructure of said optical network in at least two layers, wherein at least one selected flow-direction in one layer is distinct from all selected flow-directions in another layer, and

impose wavelength dependent rules for said optical signals.

43. The optical router of claim 42, wherein said at least two layers are interconnected at least at one of said nodes.

44. The optical router of claim 42, wherein said at least one passive wavelength filter is configured to reflect a wavelength band that includes a plurality of consecutive wavelength channels.

45. The optical router of claim 44, wherein said at least two optical signals have a same wavelength.

46. The optical router of claim 42, further comprising a combiner configured to combine a plurality of optical signals from a plurality of input ports before said passive wavelength filter routes said optical signals.

47. The optical router of claim 42, further comprising:

a plurality of input ports configured to receive a plurality of optical signals, and

wherein said at least one passive wavelength filter is configured to route at least two of said optical signals that enter different input ports to a single output port in accordance with said wavelength dependent rules and said flow-direction dependent rules.

48. The optical router of claim 42, wherein said at least one passive wavelength filter comprises a broadband wavelength filter that filters a plurality of consecutive wavelength channels.

49. The optical router of claim 42, wherein said at least one passive wavelength filter comprises a broadband thin film filter.

50. The optical router of claim 42, wherein said at least one passive wavelength filter comprises a broadband Bragg filter.

51. An optical network comprising:

network elements at nodes of said optical network, said network elements being configured to route at least one wavelength band that includes a plurality of consecutive wavelength channels; and

at least one wavelength router configured to;

impose network-wide routing restrictions restricting routing of optical signals to a selection of possible flow-directions within said optical network, said flow-directions being defined by dividing logically a physical fiber infrastructure of said optical network in at least two, wherein at least one selected flow-direction in one layer is distinct from all selected flow-directions in another layer, and

impose wavelength dependent rules for said optical signals.

52. The optical network of claim 51, wherein said at least two layers are interconnected at least at one of said nodes.

53. A method for routing optical signals through an optical network comprising a plurality of nodes with wavelength routers, said method comprising the steps of:

transmitting a plurality of optical signals from at least a number of said nodes;

receiving a plurality of optical signals at least at a number of said nodes;

imposing network-wide routing restrictions restricting routing of said optical signals at said nodes to a selection of possible flow-directions within said optical network, said flow-directions being defined by dividing logically a physical fiber infrastructure of said network in at least two layers, wherein at least one selected flow-direction in one layer is distinct from all selected flow-directions in another layer, and

imposing wavelength dependent rules for said optical signals;

wherein end-to-end paths of said optical signals through said optical network are determined by said wavelength routers.

54. The method of claim 53, wherein said flow-directions are further defined by interconnecting said at least two layers at least at one of said nodes.

55. The method of claim 53, wherein said end-to-end paths of said optical signals through said optical network are determined by said receiving step.

56. The method of claim 53, wherein said end-to-end paths of said optical signals through said optical network are determined by said transmitting step.

57. The method of claim 53, wherein at least one of said wavelength routers is configured to route at least one wavelength band that includes a plurality of consecutive wavelength channels.

58. The method of claim 53, further comprising the step of reconfiguring said wavelength dependent rules.

59. The method of claim 53, further comprising the step of reconfiguring said flow-direction rules.

60. The method of claim 53, wherein at least one of said wavelength routers comprises at least one combiner configured to combine a plurality of optical signals that enter from a plurality of input ports before said optical signals are routed to outputs of said wavelengths routers.

61. The method of claim 53, further comprising the steps of:

inputting a plurality of optical signals in a plurality of ports of said wavelength routers; and

directing the optical signals from at least two of said input ports to a same output port of said wavelength routers,

wherein said directing of said optical signals is performed in accordance with said wavelength dependent rules.

62. The method of claim 53, further comprising a number of wavelength conversion elements configured to reconfigure at least one of said flow-direction rules.

63. The method of claim 53, further comprising a number of wavelength conversion elements configured to reconfigure at least one of said wavelength dependent rules.

64. The method of claim 53, wherein said wavelength routers are configured to receive at least one first optical signal at a first input port, receive at least one second optical signal at a second input port, and route said first and second optical signals to a single output port in accordance with said wavelength dependent rules and said flow-direction dependent rules.

65. The method of claim 64, wherein optical signals that enter said at least one of said wavelength routers from different input ports, have a same wavelength, and wherein the method further comprises a step of controlling with a control system which of said at least two optical signals is transmitted in the network.

66. The method of claim 53, wherein at least one of said wavelength routers comprises at least one broadband wavelength filter configured to filter a plurality of consecutive wavelength channels.

67. The method of claim 53, wherein said transmitters transmit Internet protocol packets.

68. The method of claim 53, wherein said transmitters transmit Asynchronous Transfer Mode cells.

69. The method of claim 53, wherein:

at least a number of said nodes are connected to form a plurality of subnetworks; and

said network further comprises a top network configured to interconnect said sub-networks.

70. The method of claim 69, wherein the top network is connected to the subnetworks at a number of nodes, a number of said nodes comprising reconfigurable optical cross-connects.