Low cost secure ROADM branching unit with redundancy protection

1. A communication system, comprising:

a primary module including:

first trunk and branch input and output ports, each coupled to first in/out couplers, the first in/out couplers coupled to first circulators, and the circulators in turn coupled to first central couplers;

second trunk branch input and output ports, each coupled to second in/out couplers, each of second in/out couplers coupled to second circulators,

first and second bidirectional wavelength-selective switches (WSSes) coupled to the first central couplers; and

a secondary module including:

first trunk and branch input and output ports, each coupled to first in/out couplers, the first in/out couplers coupled to third circulators, and the circulators in turn coupled to second central couplers;

second trunk branch input and output ports, each coupled to second in/out couplers, each of second in/out couplers coupled to fourth circulators,

third and fourth bidirectional wavelength-selective switches (WSSes) coupled to the second central couplers; and

2×2 switches cross connecting the primary module WSS outputs with the secondary module WSS outputs.

2. The system of claim 1 , wherein the 2×2 optical switches comprise either 2×2 bypass switches or 2×2 cross switches.

3. The system of claim 1 , wherein at least one of the WSS is used in all paths to provide full reconfigurability and secure data delivery.

4. The system of claim 1 , comprising circulators and the bidirectional operation of WSS's within the ROADM subsystem of a submarine branching unit to reduce hardware by half.

5. The system of claim 1 , comprising a symmetric wavelength assignment module within the submarine network to provide bi-directional operations.

6. The system of claim 1 , comprising a backup WSS to provide redundancy hardware and light paths.

7. The system of claim 1 , comprising 2×2 optical switches and interconnections between working and backup components to enable full function during two simultaneous failures.

8. The system of claim 1 , wherein the WSSes have identical first wavelength configuration in a first direction and identical second wavelength configuration in a second direction.

9. The system of claim 8 , wherein the first and second wavelength configurations are complementary in a channel plan.

10. The system of claim 8 , wherein the WSSes operate simultaneously in both directions.

11. A communication system, comprising:

a primary module including:

first trunk and branch input and output ports, each coupled to first in/out couplers, the first in/out couplers coupled to first circulators, and the circulators in turn coupled to first central couplers;

second trunk branch input and output ports, each coupled to second in/out couplers, each of second in/out couplers coupled to second circulators,

first and second bidirectional wavelength-selective switches (WSSes) coupled to the first central couplers; and

a secondary module including:

first trunk and branch input and output ports, each coupled to first in/out couplers, the first in/out couplers coupled to third circulators, and the circulators in turn coupled to second central couplers;

second trunk branch input and output ports, each coupled to second in/out couplers, each of second in/out couplers coupled to fourth circulators,

third and fourth bidirectional wavelength-selective switches (WSSes) coupled to the second central couplers; and

a single 2×2 cross switch connecting the primary module WSS outputs with the secondary module WSS outputs.

12. The system of claim 11 , wherein at least one of the WSS is used in all paths to provide full reconfigurability and secure data delivery.

13. The system of claim 11 , comprising circulators and the bidirectional operation of WSS's within the ROADM subsystem of a submarine branching unit to reduce hardware by half.

14. The system of claim 11 , comprising a symmetric wavelength assignment module within the submarine network to provide bi-directional operations.

15. The system of claim 11 , comprising a backup WSS to provide redundancy hardware and light paths.

16. The system of claim 11 , comprising 2×2 optical switches and interconnections between working and backup components to enable full function during two simultaneous failures.

17. The system of claim 11 , wherein the WSSes have identical first wavelength configuration in a first direction and identical second wavelength configuration in a second direction.

18. The system of claim 17 , wherein the first and second wavelength configurations are complementary in a channel plan.

19. The system of claim 17 , wherein the WSSes operate simultaneously in both directions.

20. A communication system, comprising:

a primary module including:

first trunk and branch input and output ports, each coupled to first in/out couplers, the first in/out couplers coupled to first circulators, and the circulators in turn coupled to first central couplers;

second trunk branch input and output ports, each coupled to second in/out couplers, each of second in/out couplers coupled to second circulators,

first and second bidirectional wavelength-selective switches (WSSes) coupled to the first central couplers; and

a secondary module including:

first trunk and branch input and output ports, each coupled to first in/out couplers, the first in/out couplers coupled to third circulators, and the circulators in turn coupled to second central couplers;

second trunk branch input and output ports, each coupled to second in/out couplers, each of second in/out couplers coupled to fourth circulators,

third and fourth bidirectional wavelength-selective switches (WSSes) coupled to the second central couplers; and

one or more 2×2 switches coupling the primary module WSS outputs with the secondary module WSS outputs.