Optically-controlled optical network and switching node therefor

1. An optically-switched optical network, comprising:

information signal channels allocated to one or more optical information signals, wherein said information signal channels transmit on a fiber optic line, each respective one of said information signal channels corresponding to a respective optical wavelength range, wherein the wavelength ranges corresponding to said information signal channels are different from each other;

routing signal channels allocated to optical routing signals transmitted on said fiber optic line with the optical information signals, each respective one of said routing signal channels corresponding to a respective optical wavelength range, wherein the wavelength ranges corresponding to said routing signal channels are different from each other and are different from the wavelength ranges corresponding to said information signal channels; and

switching nodes, each comprising an optically-controlled optical switching module operable in response to at least one of the optical routing signals to switch a multi-wavelength optical signal comprising the one or more optical information signals and the optical routing signals to another of the switching nodes.

2. The optical network of claim 1 , additionally comprising:

end user devices; and

optical paths extending between the end user devices and ones of the switching nodes and among ones of the switching nodes.

3. The optical network of claim 1 , in which the optical switching module has one of the routing signal channels exclusively assigned thereto.

4. The optical network of claim 3 , in which:

the optical switching module has a default switching state; and

the optical switching module operates in response to an optical routing signal in the one of the routing signal channels to change to another switching state.

5. The optical network of claim 1 , in which the optical switching module has more than one of the routing signal channels exclusively assigned thereto.

6. The optical network of claim 5 , in which an optical routing signal in one of the exclusively-assigned routing signal channels sets the optical switching module to a respective switching state.

7. The optical network of claim 1 , in which the optical switching module is assigned a unique switch address represented by a presence of an optical routing signal in each of selected ones of the routing signal channels and an absence of an optical routing signal in others of the routing signal channels.

8. The optical network of claim 7 , in which:

the optical switching module has a default switching state; and

the optical switching module operates in response to the presence of an optical routing signal in each of the selected ones of the routing signal channels and the absence of an optical routing signal in the others of the routing signal channels to change to another switching state.

9. The optical network of claim 7 , in which ones of the routing signal channels are reserved for optical state signals.

10. The optical network of claim 9 , in which the presence of an optical routing signal in each of the selected ones of the routing signal channels and the additional presence of an optical state signal in one of the reserved routing signal channels sets the optical switching module to a respective switching state.

11. The optical network of claim 1 , in which:

the network has an available bandwidth divided into wavelength bands; and

the routing signal channels and the information signal channels are allocated among the wavelength bands.

12. The optical network of claim 11 , in which ones of the switching nodes each comprise optical switching modules equal in number to the wavelength bands.

13. An optical switching node, comprising an optically-controlled optical switching module, the optical switching module comprising:

an optical input, wherein optical information signals and routing signals are receivable at the optical input, wherein a respective information signal channels is allocated to each respective one of the optical information signals, each respective one of said information signal channels corresponding to a respective optical wavelength range, wherein the wavelength ranges corresponding to said information signal channels are different from each other, and wherein a respective routing channel is allocated to each respective one of said routing signals, each respective one of said routing signal channels corresponding to a respective optical wavelength range, wherein the wavelength ranges corresponding to said routing signal are different from each other and are different from the wavelength ranges corresponding to said information signal channels;

an optically-controlled optical switch comprising a common port, branch ports and a control port, the common port being optically associated with the optical input, the optical switch being operable in response to at least one of the optical routing signals to switch a multi-wavelength optical signal comprising the one or more optical information signals and the optical routing signals;

an optical tap comprising a main output and a sample output, the optical tap being connected to the optical input;

an optical demultiplexer connected between the sample output of the optical tap;

and the control port of the optical switch; and

an optical coupling between the main output of the optical tap and another of the ports of the optical switch.

14. The optical switching node of claim 13 , in which the optical switching module additionally comprises an optical amplifier between the sample output of the optical tap and the control port of the optical switch.

15. The optical switching node of claim 13 , in which:

the optical switching node constitutes part of an optical network; and

the demultiplexer is structured to output an optical routing signal in no more than one routing signal channel exclusively assigned to the optical switching module.

16. The optical network of claim 15 , in which:

the optical switch has a default switching state; and

the optical switch is structured to change to another switching state in response to the optical routing signal.

17. The optical switching node of claim 13 , in which:

the optical switching node constitutes part of an optical network; and

the demultiplexer is structured to provide output optical routing signals in respective routing signal channels.

18. The optical switching node of claim 13 , further comprising:

a routing signal decoder between the optical demultiplexer and the control port of the optical switch, and wherein the routing signal decoder is structured to output an optical control signal in response to receiving optical routing signals in selected ones of the routing signal channels, the selected ones of the routing signal channels representing a switch address of the optical switching module.

19. The optical network of claim 18 , in which:

the optical switch has a default switching state; and

the optical switch is structured to change to another switching state in response to the optical control signal.

20. The optical switching node of claim 18 , in which:

ones of the routing signal channels are each reserved for an optical state signal; and

the routing signal decoder is structured to operate in response to receiving optical routing signals in selected ones of the routing signal channels, the selected ones of the routing signal channels representing a switch address of the optical switching module, to output an optical control signal whose state depends on the identity of the routing signal channel in which the optical state signal is additionally received.

21. The optical switching node of claim 20 , in which the state of the optical control signal optically sets the optical switch to a respective switching state.

22. The optical switching node of claim 13 , in which the optical switching module additionally comprises:

an optical combiner interposed between the demultiplexer and the control port of the optical switch;

an additional optical tap comprising a main output and a sample output;

an additional optical demultiplexer connected between the sample output of the additional optical tap and an input of the optical combiner; and

an additional optical coupling between the main output of the optical tap and another of the ports of the optical switch.

23. The optical switching node of claim 22 , in which the optical switching module additionally comprises a routing signal decoder interposed between each of the optical demultiplexers and respective inputs of the optical combiner.

24. The optical switching node of claim 13 , additionally comprising:

additional optical switching modules, the optical switching modules each comprising a common port, a first branch port and a second branch port;

a first multiplexer comprising a common port and band ports equal in number to the

optical switching modules, each of the band ports optically connected to the common port of a respective one of the optical switching modules; and

a second multiplexer and a third multiplexer, each comprising a common port and band ports equal in number to the optical switching modules, each of the band ports of the second multiplexer optically connected to the first branch port of a respective one of the optical switching modules, each of the band ports of the third multiplexer optically connected to the second branch port of a respective one of the optical switching modules.

25. The optical switching node of claim 13 , in which the optical coupling comprises a delay element.

26. A method of routing at least one optical information signal through a network, the method comprising:

transmitting over an optical fiber a multi-wavelength optical signal comprising said at least one optical information signal and additionally comprising optical routing signals in respective routing signal channels, wherein at least one information signal channel is allocated to said at least one optical information signal, said at least one information signal channel corresponding to a respective optical wavelength range, and wherein each respective routing channel corresponds to a respective optical wavelength range, wherein the wavelength ranges corresponding to said routing signal channels are different from each other and are different from the wavelength range corresponding to said at least one information signal channel; and

at a node in the network: sampling the multi-wavelength optical signal to provide a sample, extracting from the sample the optical routing signal in at least one of the routing signal channels, and in response to the extracted optical routing signal, optically switching the multi-wavelength optical signal towards another node of the network.

27. The method of claim 26 , in which:

one of the routing signal channels is exclusively assigned to the node; and

the extracting comprises extracting the optical routing signal in the one of the routing signal channels exclusively assigned to the node.

28. The method of claim 26 , in which:

two of the routing signal channels are exclusively assigned to the node; and

the extracting comprises extracting the optical routing signals in the two of the routing signal channels assigned exclusively to the node.

29. The method of claim 26 , in which:

optical routing signals in selected ones of the routing signal channels represent an address of the node;

the extracting comprises extracting optical routing signals in the ones of the routing signal channels to provide an optical control signal; and

the optical switching comprises switching the multi-wavelength optical signal in response to the optical control signal.