All optical variable buffer queue useful in optical packet networks

• US 20050053375A1
• Filed: 09/02/2004
• Published: 03/10/2005
• Est. Priority Date: 09/04/2003
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Yoo, SungJoo Ben, Yang, Haijun
• Granted Patent: US 7,313,329 B2
• Time in Patent Office: Days
• US Class Current: 398/53
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/002 using optical delay lines or optical buffers or optical recirculation

Abstract

A variable optical buffer queue, particularly useful either as an input or an output queue in an optical packet router in a wavelength-division multiplexing (WDM) communication network. An input queue includes plural separately controllable optical delay units disposed on wavelength channels between a demultiplexer and tunable wavelength converters controlling switching through a wavelength router. An output queue includes for each output port of a wavelength router plural separately controllable optical delay units tuned to different wavelengths. The delay units may induce selective amounts of delay and may be implemented as a series of controlled microresonators coupled to waveguide. Such a structure is usable as a controllably accessible optical memory.

Claims

1. An optical routing system, comprising:

an all-optical router for selectively routing optical packets between a plurality of optical inputs and a plurality of optical outputs; and

a variable optical buffer queue associated with said router for selectively buffering selected ones of said packets.

2. The system of claim 1, wherein said optical router comprises a wavelength router having a plurality of switching inputs and a plurality of switching outputs.

3. The system of claim 2, wherein said variable optical buffer queue comprises an input queue connected between said optical inputs and said switching inputs.

4. The system of claim 2, wherein said variable optical buffer queue comprises an output queue connected between said switching outputs and said optical outputs.

7. The optical router of claim 4, wherein said variable optical delays are implemented in a semiconductor structure.

8. The optical router of claim 7, wherein said third optical paths include respective optical waveguides and said variable optical delays include a respective plurality of microresonators arranged along each of said waveguides.

5. An optical router, comprising:

at least one demultiplexer receiving a multi-wavelength signal on an input port and demultiplexing it onto a plurality of first optical paths;

an optical routing system including input ports connected to said first optical paths and switching optical signals received at said input ports to output ports dependent upon carrier wavelengths of said optical signals second optical paths receiving signals from said outputs ports;

at least one demultiplexer having an input port receiving said second optical paths; and

electrically controllable variable optical delays disposed on respective third optical paths including said first and second optical paths to selectively delay optical signals having selected optical carriers.

6. The optical router of claim 5, integrated into a semiconductor substrate.

9. The optical router of claim 5, wherein said variable optical delays are disposed along said first optical paths.

10. The optical router of claim 5, wherein said variable optical delays are disposed along said second optical paths.

11. The optical router of claim 10, wherein said variable optical delays comprise a plurality of optical delays specifically identified to different carrier wavelengths and serially arranged along said second optical paths.

12. The optical router of claim 5, wherein said optical routing system comprises a wavelength router and further comprising:

tunable wavelength converters disposed on said first optical paths adjacent to said input ports; and

wavelength converters disposed on said second optical paths adjacent to said output ports.

13. An optical router, comprising:

at least one optical demultiplexer receiving a respective multi-wavelength signal and demultiplexing it into a plurality of respective wavelength channels;

a separately controllable optical delay unit disposed on each of said wavelength channels;

a plurality of variable wavelength converters receiving the respective outputs of the optical delay units; and

a wavelength router receiving optical signals from said variable wavelength converters on input ports and switching them to selected ones of output ports according to wavelengths determined by said variable wavelength converters.

14. The router of claim 13, further comprising;

a plurality of output wavelength converters receiving signals from said output ports; and

a plurality of optical multiplexers receiving outputs of respective output wavelength converters.

15. The optical router of claim 13, wherein said at least one optical demultiplexer comprises a plurality of said optical demultiplexers.

16. The optical router of claim 13, wherein said controllable optical delay unit can control the delay to a plurality of finite values, for example, a two-bit or larger digital value.

17. An optical router, comprising:

at least one optical demultiplexer receiving a respective multi-wavelength signal and demultiplexing it into a plurality of respective wavelength channels;

a plurality of variable wavelength converters receiving the respective outputs of the at least one optical demultiplexer;

a wavelength router receiving optical signals from said variable wavelength converters on input ports and switching them to selected ones of output ports according to wavelengths determined by said variable wavelength converters; and

a separately controllable multi-stage optical delay unit connected to each of said output ports and in addition separately delaying a plurality of wavelength channels.

18. The router of claim 17, further comprising:

a plurality of output wavelength converters receiving signals from said delay units;

a plurality of optical multiplexers receiving outputs of respective output wavelength converters.

19. The router of claim 17, wherein said optical delay unit comprises a plurality of serially connected components, each of which is transparent to all but one of a plurality of switching wavelengths.

20. The router of claim 17, wherein said least one optical demultiplexer comprises a plurality of said optical demultiplexers.

21. The router of claim 17, wherein said multi-stage delay unit provides for a plurality of finite delays for each of a plurality of said wavelength channels, for example, any of two-bit or greater digital values.

22. An optical router, comprising:

at least one optical demultiplexer receiving a multi-wavelength signal and demultiplexing it into a plurality of respective wavelength channels;

a separately controllable optical delay unit disposed on each of said wavelength channels;

a plurality of variable wavelength converters receiving the respective outputs of the optical delay units;

a wavelength router receiving optical signals from said variable wavelength converters on input ports and switching them to selected ones of output ports according to wavelengths determined by said variable wavelength converters;

a separately controllable multi-stage optical delay unit connected to each of said output ports and additionally separately delaying a plurality of wavelength channels;

a plurality of output wavelength converters receiving signals from said multi-stage optical delay units; and

a plurality of optical multiplexers receiving outputs of respective output wavelength converters.

23. An optical switching system, comprising:

a wavelength router switching optical signals from a plurality of input ports to selected ones of a plurality of output ports according to optical wavelengths of said optical signals; and

separately controllable multi-stage optical delay units connected to each of said output ports and additionally separately delaying selected ones of a plurality of wavelength channels passing therethrough.

24. A wavelength routing method, comprising the steps of:

demultiplexing a first multi-wavelength signal into a plurality of single-wavelength signals;

converting a carrier wavelengths of one of said single-wavelength signals to a switching wavelength;

routing said one single-wavelength signal in a directions in accordance with said switching wavelength;

multiplexing multiple ones of said routed single-wavelength signals into a second multi-wavelength signal; and

between said demultiplexing and said multiplexing steps, imposing a selected delay amount upon said one single-wavelength signal.

25. The method of claim 24, wherein said imposing step applies an electrical signal to an electrode associated with a plurality of microresonators operatively associated with a waveguide carrying said one single-wavelength signal.

26. An optical memory, comprising:

a first plurality of microresonators arranged along and coupled to an optical waveguide; and

at least one electrode operatively coupled to at least one of said optical waveguide and said microresonators to affect a coupling therebetween, a biasing of said at least one electrode determining a delay of an optical signal along said waveguide.

27. A multi-wavelength optical memory, comprising:

a waveguide capable of carrying a multi-wavelength optical signal; and

a plurality of delay units disposed along said waveguide and associated with respective wavelength components of said multi-wavelength optical signal, each of said delay units including an electrical control to selectively control different ones of said delay units to induce a time delay into respective ones of said wavelength components.

28. The memory of claim 27, further comprising a controller separately controlling said electrical controls of said plurality of delay units.

29. The memory of claim 27, wherein each of said delay units comprises a plurality of microresonators arranged along said optical waveguide.