Metropolitan photonic switch

• US 20040184714A1
• Filed: 02/02/2004
• Published: 09/23/2004
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Graves, Alan F., Irwin, George, Watkins, John H.
• Granted Patent: US 7,050,667 B2
• Time in Patent Office: Days
• US Class Current: 385/16
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0208 Interleaved arrangements
• 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 14/022 For interconnection of WDM optical networks
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/0284 WDM mesh architectures
• CPC Class Codes: H04J 14/0289 Optical multiplex section protection
• CPC Class Codes: H04J 14/0297 Optical equipment protection
• CPC Class Codes: H04Q 11/0005 Switch and router 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 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0075 Wavelength grouping or hierarchical aspects

Abstract

A photonic switch uses a cost-effective DWDM optimized switch architecture allowing the introduction of DWDM into the metro network. In order to implement this architecture cost-effective ways of implementing the optical carrier frequency/wavelength precision required for a Dense Wavelength Division Multiplexing 100 GHz or 50 GHz on-grid solutions are needed. The photonic switch acts as an intermediary between the WDM density of the access portion of the metropolitan photonic network and the DWDM density of the core photonic network. The metro photonic switch introduces optical carriers that are all generated in the photonic layer adjacent to it and allocates them out to the photonic access nodes for modulation. This has the advantage of providing the optical carriers to be modulated from a centralized highly stable and precise source, thereby meeting the requirements for DWDM carrier precision, whilst generating these carriers in relatively close proximity to the modulators. Coarse WDM components can be used in the access portion of the network without adversely affecting the ability of the signal to transit the DWDM portion of the core network, since the optical carrier frequency is fixed at the centralized source and is unaffected by these components.

Claims

1. An optical switching node for a photonic network comprising:

a photonic switch core having a plurality of inputs and a plurality of outputs and capable of connecting any input to any output;

a first wavelength division demultiplexer coupled to a subset of the plurality of inputs for demultiplexing an optical signal having a first multiplex density having a first wavelength spacing into optical channels; and

a first wavelength division multiplexer coupled to a subset of the plurality of outputs for multiplexing any optical channels connected to it into an optical signal having a second multiplex density having a second wavelength spacing;

the second multiplex density being higher than the first.

2. An optical switching node as claimed in claim 1 wherein the first wavelength spacing is k times the second wavelength spacing, where k is an integer.

3. An optical switching node as claimed in claim 2 wherein the first wavelength division multiplexer includes N ports connected to N wavelength plane switches.

4. An optical switching node as claimed in claim 1 further comprising a second wavelength division demultiplexer coupled to a second subset of the plurality of inputs for demultiplexing an optical signal having the second multiplex density into optical channels.

5. An optical switching node as claimed in claim 4 wherein the first wavelength spacing is k times the second wavelength spacing, where k is an integer.

6. An optical switching node as claimed in claim 5 wherein the first wavelength division multiplexer includes N ports connected to N wavelength plane switches.

7. An optical switching node as claimed in claim 1 further comprising a second wavelength division multiplexer coupled to a second subset of the plurality outputs for multiplexing an optical signal having the first multiplex density into optical channels.

8. An optical switching node as claimed in claim 7 wherein the first wavelength spacing is k times the second wavelength'"'"'spacing, where k is an integer.

9. An optical switching node as claimed in claim 8 wherein the first wavelength division multiplexer includes N ports connected to N wavelength plane switches.

10. An optical switching node as claimed in claim 1 wherein the photonic switch core is operable to consolidate wavelengths from access multiplexers into a dense wavelength division multiplexed (DWDM) signal for transmission in a core network;

and

including a multi-wavelength source for generating DWDM quality wavelengths for supplying the access multiplexers with unmodulated wavelengths upon which to multiplex data packets.

11. An optical switching node as claimed in claim 10 wherein the photonic switch core is capable of switching at the wavelength, group of wavelength, and fiber level.

12. An optical switching node as claimed in claim 1 further comprising a core node, coupled to the photonic switch core via a plurality of fiber optic cable for carrying a similar plurality of wavelengths from a DWDM signal, and operable to route the data packets modulated on the wavelengths within a communications network or out to a long haul network.

13. An optical switching node as claimed in claim 12 wherein the core node is capable of switching at the wavelength, group of wavelength, and fiber level.

14. An optical switching node as claimed in claim 12 wherein the core node includes a wavelength converter for converting one wavelength to another wavelength to provide an end-to-end photonic connection across the network.

15. An optical switching node as claimed in claim 14 wherein the wavelength converter includes opto-electronic devices.

16. A network as claimed in claim 15 wherein the wavelength converter includes photonic devices.

17. An optical switching node as claimed in claim 16 wherein the core node includes a packet router and a photonic switch coupled together to effect packet level switching for packets originating at access multiplexers.

18. An optical switching node as claimed in claim 17 wherein the core node includes a wavelength converter coupled to the photonic switch to effect an all photonic connection through the network.

19. An optical switching node as claimed in claim 18 wherein the photonic switch core includes a first plurality of input ports and a second plurality of output ports, with the first being greater than the second, whereby the photonic switch effects concentration of the wavelengths from the access multiplexers.