Concatenated optical spectrum transmission systems and methods

• US 9,197,354 B2
• Filed: 08/26/2011
• Issued: 11/24/2015
• Est. Priority Date: 08/26/2010
• Status: Active Grant

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Boertjes, David, Belanger, Michel
• Primary Examiner(s): Vanderpuye, Ken
• Assistant Examiner(s): SANDHU, AMRITBIR K
• Application Number:
  US13/218,759
• Publication Number:
  US 20120219293A1
• Time in Patent Office: 1,551 Days
• Field of Search: 398/48, 398/69
• US Class Current: 1/1
• CPC Class Codes: H04J 14/0204 Broadcast and select arrangements, e.g. with an optical splitter at the input before adding or dropping
• CPC Class Codes: H04J 14/0206 Express channels 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 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04J 14/0257 Wavelength assignment algorithms
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0086 Network resource allocation, dimensioning or optimisation

Abstract

The present disclosure relates to concatenated optical spectrum transmission systems and methods that allocate optical spectrum of groups of channels to reduce or eliminate deadbands or guardbands (i.e., unused optical spectrum) between channels. The concatenated optical spectrum transmission systems and methods include various techniques for using optical spectrum such as over the C-band or any other frequency bands. In particular, the concatenated optical spectrum transmission systems and methods provide a balance between fixed channel systems such as provided for by the International Telecommunication Union (ITU) and a more flexible system enabled by coherent optical detection. In an exemplary embodiment, the concatenated optical spectrum transmission systems and methods may utilize a Wavelength Selective Switch (WSS) and a plurality of moderate Common Mode Rejection Ratio (CMRR) coherent receivers in combination to achieve a concatenated optical spectrum.

Claims

1. An optical network, comprising:

a first network element with an add Wavelength Selective Switch (WSS);

a second network element with a drop WSS communicatively coupled to the add WSS of the first network element by a first optical fiber, wherein the first optical fiber includes a first plurality of optical channels and a second plurality of optical channels;

wherein each of the first plurality of optical channels are located on an optical spectrum over the first optical fiber with substantially no spectrum between adjacent channels, and wherein each of the second plurality of optical channels are located on the optical spectrum with substantially no spectrum between adjacent channels;

wherein a plurality of bins are defined directly adjacent to and touching one another over the optical spectrum by a management system for operations, administration, maintenance, and provisioning of the optical network, wherein each of the first plurality of optical channels and the second plurality of optical channels are assigned to a variable number of the plurality of bins, and wherein a width of each of the plurality of bins is smaller than or equal to a smallest required roll-off on the add WSS, the drop WSS, or any wavelength selective components in the optical network; and

wherein at least one channel of the first plurality of optical channels or the second plurality of optical channels is assigned to more than one bin.

2. The optical network of claim 1, wherein a guardband is defined on the optical spectrum between one end of the first plurality of optical channels and one end of the second plurality of optical channels, wherein the guardband is equal to one bin.

3. The optical network of claim 1, further comprising, at the second network element:

a first power splitter coupled to a drop port of the drop WSS; and

a first plurality of Common Mode Rejection Ratio (CMRR) coherent optical receivers coupled to the power splitter, wherein each of the first plurality of CMRR coherent optical receivers receives each of the first plurality of optical channels and selectively receives one of the first plurality of optical channels.

4. The optical network of claim 1, wherein the drop WSS has a continuous spectral response on adjacent actuated portions of the optical spectrum when pointed to the same port.

5. The optical network of claim 1, further comprising:

a third network element with a second drop WSS communicatively coupled to a second add WSS at the second network element by a second optical fiber, wherein the second drop WSS and the second add WSS are part of the wavelength selective components;

wherein the second plurality of optical channels is communicated over the second optical fiber and the first optical fiber.

6. The optical network of claim 1, wherein at least two of the first plurality of optical channels have a different baud rate.

7. The optical network of claim 1, wherein all channels in the first plurality of optical channels have a same A-Z path in the optical network, wherein all channels in the second plurality of optical channels have a same A-Z path in the optical network, and wherein the first plurality of optical channels have a different A-Z path in the optical network from the second plurality of optical channels.

8. The optical network of claim 1, wherein the first plurality of channels are dropped at the second network element via the drop WSS which is configured to filter each of the first plurality of channels instead of individual channel filtering via a demultiplexer at the second network element.

9. An optical system, comprising:

a flexible spectrum wavelength selective switch configured to receive a wavelength division multiplexed (WDM) signal with at least one drop port configured to receive a first group of optical channels from the WDM signal with adjacent channels spectrally spaced substantially next to one another;

a power splitter coupled to the at least one drop port; and

a plurality of Common Mode Rejection Ratio (CMRR) coherent optical receivers coupled to the power splitter, wherein each of the CMRR coherent optical receivers receives each of the first group of optical channels and selectively receives one of the first group of optical channels;

wherein the first group of optical channels occupy a variable number of bins defined directly adjacent to and touching one another and over an optical spectrum by a management system for operations, administration, maintenance, and provisioning of the optical network, and wherein a width of each of the bins is smaller than or equal to a smallest required roll-off on the flexible spectrum wavelength selective switch or any wavelength selective component in an optical network associated with the optical system; and

wherein at least one channel of the first group of optical channels occupies more than one bin.

10. The optical system of claim 9, wherein the flexible spectrum wavelength selective switch has a continuous spectral response on adjacent actuated portions of the optical spectrum when pointed to the at least one drop port.

11. The optical system of claim 9, wherein the flexible spectrum wavelength selective switch further comprises at least one express port configured to receive a second group of optical channels from the WDM signal, wherein the optical spectrum of the WDM signal has a guardband of one bin between the first group of optical channels and the second group of optical channels.

12. The optical system of claim 11, wherein all channels in the first group of optical channels have a same A-Z path in the optical network, wherein all channels in the second group of optical channels have a same A-Z path in the optical network, and wherein the first group of optical channels have a different A-Z path in the optical network from the second group of optical channels.

13. The optical system of claim 11, wherein the first group of optical channels are dropped via flexible spectrum wavelength selective switch which is configured to filter each of the first group of optical channels instead of individual channel filtering via a demultiplexer.

14. A method, comprising:

determining a plurality of bins defined directly adjacent to and touching one another over an optical spectrum associated with an optical fiber in an optical network by a management system for operations, administration, maintenance, and provisioning of the optical network;

dropping a first optical signal to a first coherent optical receiver, wherein the first optical signal uses one or more bins of the plurality of bins; and

dropping a second optical signal to a second coherent optical receiver, wherein the second optical signal uses one or more of adjacent bins to the one or more bins used by the first optical signal;

wherein each of the first optical signal and the second optical signal are assigned to a variable number of the plurality of bins, and wherein a width of each of the plurality of bins is smaller than or equal to a smallest required roll-off on any wavelength selective component in the optical network; and

wherein at least one of the first optical signal and the second optical signal uses more than one bin, and wherein the first optical signal and the second optical signal have a same A-Z path in the optical network.

15. The method of claim 14, further comprising:

determining guardbands in one or more of the plurality of bins, wherein the guardbands are spectrally defined as one bin and placed between groups of channels with different A-Z paths in the optical network.

16. The method of claim 14, wherein the number of bins for each of the first optical signal and the second optical signal is based on a format and baud rate associated therewith.

17. The method of claim 14, further comprising:

utilizing the management system to provision the first optical signal in the one or more bins.

18. The method of claim 14, wherein all optical channels in the optical network have the same A-Z path in the optical network and the optical spectrum has no guardbands or deadbands between adjacent channels.