Sub-wavelength granularity for transport of multicarrier optical signals
AssigneeAlcatel-Lucent USA Inc.
InventorsNoriaki Kaneda, Sian Chong J. Lee
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Abstract
We disclose an optical add-drop multiplexer that can apply different routing operations to different subcarriers of a data frame. In an example embodiment, the digital signal processor (DSP) of the optical add-drop multiplexer carries out subcarrier-specific add, drop, and pass-through operations in the electrical frequency domain, which enables the DSP to only partially unwrap the pass-through subcarriers, thereby at least partially avoiding some of the more processing-power-hungry DSP operations and reducing the sub-wavelength routing latency accordingly. Also disclosed is an example data-frame structure that can be used to provide subcarrier-specific routing instructions to the optical add-drop multiplexer.
Claims17
An apparatus comprising an optical add-drop multiplexer configured to receive a first optical signal and to generate a second optical signal, each of the first and second optical signals being an optical orthogonal frequency-division multiplexed (OFDM) signal, wherein the optical add-drop multiplexer comprises a first receiver branch and a first transmitter branch;
- wherein the first receiver branch is configured to:
- apply a Fourier-transform operation to a first digital time-domain signal corresponding to the first optical signal to generate a first set of digital spectral components, each corresponding to a respective OFDM subcarrier;
- transfer a first subset of the first set of digital spectral components to the first transmitter branch;
- and
- process a second subset of the first set of digital spectral components to generate a first output data stream that carries data encoded in the second subset of the first set of digital spectral components;
- wherein the first transmitter branch is configured to apply an inverse Fourier-transform operation to a second set of digital spectral components, each corresponding to a respective OFDM subcarrier, to generate a second digital time-domain signal, wherein the second set of digital spectral components includes the first subset of the first set of digital spectral components received from the first receiver branch;
- wherein the optical add-drop multiplexer is further configured to use the second digital time-domain signal to generate the second optical signal in a manner that causes the second optical signal to carry data encoded in the first subset of the first set of digital spectral components;
- wherein the optical add-drop multiplexer is configured to read one or more add-drop-through (ADT) indices from a header of a data frame carried by the first optical signal;
- and
- wherein the first receiver branch is configurable to sort the first set of digital spectral components into the first subset and the second subset thereof using the one or more ADT indices.
An apparatus comprising an optical add-drop multiplexer configured to receive a first optical signal and to generate a second optical signal, each of the first and second optical signals being an optical orthogonal frequency-division multiplexed (OFDM) signal, wherein the optical add-drop multiplexer comprises a first receiver branch and a first transmitter branch;
- wherein the first receiver branch is configured to:
- apply a Fourier-transform operation to a first digital time-domain signal corresponding to the first optical signal to generate a first set of digital spectral components, each corresponding to a respective OFDM subcarrier;
- and
- transfer a first subset of the first set of digital spectral components to the first transmitter branch;
- and
- wherein the first transmitter branch is configured to:
- receive a first input data stream;
- generate a second subset of digital spectral components having encoded thereon data carried by the first input data stream;
- and
- apply an inverse Fourier-transform operation to a second set of digital spectral components, each corresponding to a respective OFDM subcarrier, to generate a second digital time-domain signal, wherein the second set of digital spectral components includes the first subset of the first set of digital spectral components received from the first receiver branch and the second subset of digital spectral components;
- wherein the optical add-drop multiplexer is further configured to use the second digital time-domain signal to generate the second optical signal in a manner that causes the second optical signal to carry data encoded in the first subset of the first set of digital spectral components and in the second subset of digital spectral components;
- wherein the optical add-drop multiplexer is configured to read one or more add-drop-through (ADT) indices from a header of a data frame carried by the first optical signal;
- and
- wherein the first transmitter branch is configurable to generate the second subset of digital spectral components using the one or more ADT indices.
Dependencies are inferred from the claim text.