Synchronous optical network in frequency domain

A method of optical communication, comprising:

• separating a first input wavelength division multiplexed (WDM) signal received from a first optical path into a first plurality of subsets of wavelength signals;
• separating a second input WDM signal received from a second optical path into a second plurality of subsets of wavelength signals;
• interchanging wavelength signals between particular subsets of wavelength signals associated with the first and second input WDM signals such that at least one wavelength signal from a particular subset of the first input WDM signal is communicated to the second optical path and at least one wavelength signal from a particular subset of the second input WDM signal is communicated to the first optical path;
• wherein the wavelength signals interchanged between the first and second optical paths comprise different wavelengths, and further comprising converting one of the interchanged wavelength signals to approximately match the wavelength of the signal being interchanged.

A node in an optical communication system, the node comprising:

• a first demultiplexer operable to receive a first input wavelength division multiplexed (WDM) signal from a first optical path coupled to then ode and to separate the first input WDM signal into a plurality of subsets of wavelength signals;
• a second demultiplexer operable to receive a second input WDM signal from a second optical path coupled to the node and to separate the second input WDM signal into a plurality of subsets of wavelength signals;
• wherein at least one of the first and second input WDM signals comprises a first beam and a second beam, and wherein the demultiplexer receiving the at least one signal comprises:
• an optical filter operable to decompose the second beam into a fifth beam and a sixth beam;
• wherein the third beam and the fifth beam carry the first subset of wavelength signals and the fourth beam and the sixth beam carry the second subset of wavelength signals;
• and
• wherein the third beam and the sixth beam have a first polarization and the fourth beam and the fifth beam have a second polarization that is transverse to the first polarization;
• and
• an optical cross connect operable to receive only particular subsets of wavelength signals from the first and second input WDM signals, and to interchange wavelength signals between the particular subsets such that at least one wavelength signal from the particular subset of first input WDM signal is communicated to the second optical path and at least one wavelength signal from the particular subset of second input WDM signals is communicated to the first optical path.

A method of communicating optical signals, comprising:

• receiving an input wavelength division multiplexed (WDM) signal comprising a plurality of wavelength signals;
• separating the input WDM signal into at least a first subset of wavelength signals comprising a first plurality of wavelengths and a second subset of wavelength signals comprising a second plurality of wavelengths different from and interdigitally spaced among the first plurality of wavelengths;
• communicating the first subset of wavelength signals using an express path without further processing;
• communicating the second subset of wavelength signals using a processing path;
• and
• performing a signal processing function on at least a portion of the second subset of wavelength signals, wherein performing a signal processing function comprises routing at least some of the second subset of wavelength signals for receipt by another node in the system without converting the at least some of the wavelength signals to an electrical format.

A method of optical communication, comprising:

• receiving a first input wavelength division multiplexed (WDM) signal comprising a first beam and a second beam;
• filtering the first input WDM signal using an optical filter operable to decompose the first beam into a third beam and a fourth beam and to decompose the second beam into a fifth beam and a sixth beam, wherein the third beam and the fifth beam carry a first subset of wavelength signals and the fourth beam and the sixth beam carry a second subset of wavelength signals, wherein the third beam and the sixth beam have a first polarization and the fourth beam and the fifth beam have a second polarization that is transverse to the first polarization;
• separating a second input WDM signal received from a second optical path into a plurality of subsets of wavelength signals;
• interchanging wavelength signals between particular subsets of wavelength signals associated with the first and second input WDM signals such that at least one wavelength signal from a particular subset of the first input WDM signal is communicated to the second optical path and at least one wavelength signal from a particular subset of the second input WDM signal is communicated to the first optical path.

In an optical communication system comprising a plurality of optical paths, a node coupled to at least one of the optical paths, the node comprising

• a demultiplexer operable to receive a WDM signal comprising a first beam and a second beam, wherein the demultiplexer comprises:
• an optical filter operable to decompose the first beam into a third beam and a fourth beam and to decompose the second beam into a fifth beam and a sixth beam;
• wherein the third beam and the fifth beam carry the first subset of wavelength signals and the fourth beam and the sixth beam carry the second subset of wavelength signals, and wherein the first and second pluralities of wavelength signals are processed differently depending on the wavelengths in each plurality of wavelength signals;
• and
• wherein the third beam and the sixth beam have a first polarization and the fourth beam and the fifth beam have a second polarization that is transverse to the first polarization;
• an express path operable to receive from the demultiplexer the first subset of wavelength signals, and to pass those wavelength signals from the node without further processing;
• and
• a processing path operable to receive from the demultiplexer the second subset of wavelength signals such that those wavelength signals are processed within the node.

In an optical communication system comprising a plurality of optical paths, a node coupled to at least one of the optical paths, the node comprising:

• a demultiplexer operable to receive a first input wavelength division multiplexed (WDM) signal and to separate the input WDM signal into at least a first subset of wavelength signals comprising a first plurality of wavelengths and a second subset of wavelength signals comprising a second plurality of wavelengths different from the first plurality of wavelengths, wherein the first and second pluralities of wavelength signals are processed differently depending on the wavelengths in each plurality of wavelength signals;
• an express path operable to receive from the demultiplexer the first subset of wavelength signals, and to pass those wavelength signals from the node without further processing;
• and
• an optical cross connect operable to receive the second subset of wavelength signals of the first input WDM signal and to receive a third subset of wavelength signals of a second input WDM signal, the optical cross connect operable to selectively substitute a wavelength signal from the third subset for a wavelength signal of the second subset of wavelength signals;
• wherein the wavelength signal from the third subset and the wavelength signal from the second subset comprise different wavelengths, and wherein the optical cross connect comprises a wavelength converter operable to convert the wavelength signal of the third subset to approximately match the wavelength of the wavelength signal of the second subset.

In an optical communication system comprising a plurality of optical paths, a node coupled to at least one of the optical paths, the node comprising:

• a demultiplexer operable to receive an input wavelength division multiplexed (WDM) signal and to separate the input WDM signal into at least a first subset of wavelength signals comprising a first plurality of wavelengths and a second subset of wavelength signals comprising a second plurality of wavelengths different from the first plurality of wavelengths, wherein the first and second pluralities of wavelength signals are processed differently depending on the wavelengths in each plurality of wavelength signals;
• an express path operable to receive from the demultiplexer the first subset of wavelength signals, and to pass those wavelength signals from the node without further processing;
• and
• a processing path operable to receive from the demultiplexer the second subset of wavelength signals, the processing path comprising:
• a protection path operable to facilitate routing at least some of the second subset of wavelength signals to another node in the communication system along a second communication path after detection of a fault along a first communication path between the node to the another node;
• wherein the second subset of wavelength signals comprises a traffic subset and a protection subset, and wherein the node is operable to dynamically allocate wavelength signals between the traffic subset and the protection subset.

A node in an optical communication system, the node comprising:

• a first demultiplexer operable to receive a first input wavelength division multiplexed (WDM) signal from a first optical path coupled to the node and to separate the first input WDM signal into a plurality of subsets of wavelength signals;
• a second demultiplexer operable to receive a second input WDM signal from a second optical path coupled to the node and to separate the second input WDM signal into a plurality of subsets of wavelength signals;
• and
• an optical cross connect operable to receive only particular subsets of wavelength signals from the first and second input WDM signals, and to interchange wavelength signals between the particular subsets such that at least one wavelength signal from the particular subset of first input WDM signals is communicated to the second optical path and at least one wavelength signal from the particular subset of second input WDM signals is communicated to the first optical path;
• wherein the wavelength signals interchanged between the first and second optical paths comprise different wavelengths, and wherein the optical cross connect comprises a wavelength converter operable to convert one of the interchanged wavelength signals to approximately match the wavelength of the other interchanged wavelength signal.

A method of communicating optical signals, comprising:

• receiving an input wavelength division multiplexed (WDM) signal comprising a first beam and a second beam;
• filtering the input WDM signal using an optical filter operable to decompose the first beam into a third beam and a fourth beam and to decompose the second beam into a fifth beam and a sixth beam, wherein the third beam and the fifth beam carry a first subset of wavelength signals and the fourth beam and the sixth beam carry a second subset of wavelength signals, and wherein the third beam and the sixth beam have a first polarization and the fourth beam and the fifth beam have a second polarization that is transverse to the first polarization;
• communicating the first subset of wavelength signals using an express path without further processing;
• communicating of the second subset of wavelength signals using a processing path;
• and
• performing a signal processing function on at least a portion of the second subset of wavelength signals.

A method of communicating optical signals, comprising:

• receiving a first input wavelength division multiplexed (WDM) signal comprising a plurality of wavelength signals;
• separating the input WDM signal into at least a first subset of wavelength signals comprising a first plurality of wavelengths and a second subset of wavelength signals comprising a second plurality of wavelengths different from the first plurality of wavelengths;
• communicating the first subset of wavelength signals using an express path without further processing;
• receiving a third subset of wavelength signals associated with a second input WDM signal;
• converting the wavelength of a wavelength signal from the third subset to at least approximately match a wavelength of a selected one of the wavelength signals from the second subset;
• and
• substituting the converted wavelength signal from the subset of wavelength signals with the selected one of the wavelength signals from the second subset of wavelength signals.

A method of communicating optical signals, comprising:

• receiving an input wavelength division multiplexed (WDM) signal comprising a plurality of wavelength signals;
• separating the input WDM signal into at least a first subset of wavelength signals comprising a first plurality of wavelengths and a second subset of wavelength signals comprising a second plurality of wavelengths different from the first plurality of wavelengths, wherein the second subset of wavelength signals comprises a traffic subset and a protection subset;
• communicating the first subset of wavelength signals using an express path without further processing;
• communicating of the second subset of wavelength signals using a processing path;
• and
• performing a signal processing function on at least a portion of the second subset of wavelength signals, the signal processing function comprising:
• routing at least some of the second subset of wavelength signals to another node in the communication system along a second communication path after detection of a fault along a first communication path between the node to the another node;
• and
• dynamically allocating wavelength signals between the traffic subset and the protection subset.