US 9,960,845 B2Granted

In-band optical-link monitoring for a WDM network

AssigneeAlcatel-Lucent USA Inc.

InventorsDat D. Ngo, Jonathan Nagel

Life of this patent

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Abstract

We disclose embodiments of a WDM transmitter having an in-band OTDR capability for at least a subset of the WDM channels thereof. In an example embodiment, an OTDR-enabled WDM channel of the WDM transmitter is implemented using an optical transceiver that comprises an optical transmitter and a coherent optical receiver. The optical transmitter is configured to generate a modulated optical signal by modulating a respective carrier wavelength, transmit the modulated optical signal through an optical link as a component of the corresponding WDM signal, and provide the respective carrier wavelength to the coherent optical receiver for being used therein as an optical local oscillator. The optical receiver is configured to estimate an impulse response of the optical link by coherently detecting and processing a return optical signal produced within the optical link due to distributed reflection and/or backscattering of the modulated optical signal.

Claims27

Dependent claims

An apparatus comprising:

a first transceiver configured to generate a first modulated optical signal having a first carrier wavelength;
a second transceiver configured to generate a second modulated optical signal having a different second carrier wavelength;
and
an optical multiplexer configured to multiplex the first modulated optical signal and the second modulated optical signal to generate a first WDM signal;
wherein the apparatus is capable of transmitting the first WDM signal to a first optical link and receiving back from the first optical link a second WDM signal;
wherein the optical multiplexer is further configured to demultiplex the second WDM signal to generate a first return optical signal and a second return optical signal;
wherein the first transceiver is further configured to determine a first correlation between the first modulated optical signal and the first return optical signal;
wherein the second transceiver is further configured to determine a second correlation between the second modulated optical signal and the second return optical signal;
and
wherein the first transceiver is configured to:
generate the first modulated optical signal in a manner that causes the first modulated optical signal to have a first modulated component of a first polarization and a second modulated component of a second polarization, the second modulated component being modulated independent of the first modulated component, the second polarization being orthogonal to the first polarization;
and
determine the first correlation using a first correlation function and a second correlation function, the first correlation function correlating the first modulated component and the first return optical signal, and the second correlation function correlating the second modulated component and the first return optical signal.

10 more elements

An apparatus comprising:

a first transceiver configured to generate a first modulated optical signal having a first carrier wavelength;
a second transceiver configured to generate a second modulated optical signal having a different second carrier wavelength;
and
an optical multiplexer configured to multiplex the first modulated optical signal and the second modulated optical signal to generate a first WDM signal;
wherein the apparatus is capable of transmitting the first WDM signal to a first optical link and receiving back from the first optical link a second WDM signal;
wherein the optical multiplexer is further configured to demultiplex the second WDM signal to generate a first return optical signal and a second return optical signal;
wherein the first transceiver is further configured to determine a first correlation between the first modulated optical signal and the first return optical signal;
wherein the second transceiver is further configured to determine a second correlation between the second modulated optical signal and the second return optical signal;
wherein the first transceiver is further configured to:
generate the first modulated optical signal by modulating a first carrier wave having the first carrier wavelength;
generate one or more first electrical signals by coherently detecting the first return optical signal using a split portion of the first carrier wave as an optical local oscillator;
and
determine the first correlation using the one or more first electrical signals;
and
wherein the first transceiver includes an optical filter configured to filter the first return optical signal prior to the first return optical signal being coherently detected.

12 more elements

An apparatus comprising:

a first transceiver configured to generate a first modulated optical signal having a first carrier wavelength;
a second transceiver configured to generate a second modulated optical signal having a different second carrier wavelength;
and
an optical multiplexer configured to multiplex the first modulated optical signal and the second modulated optical signal to generate a first WDM signal;
wherein the apparatus is capable of transmitting the first WDM signal to a first optical link and receiving back from the first optical link a second WDM signal;
wherein the optical multiplexer is further configured to demultiplex the second WDM signal to generate a first return optical signal and a second return optical signal;
wherein the first transceiver is further configured to determine a first correlation between the first modulated optical signal and the first return optical signal;
wherein the second transceiver is further configured to determine a second correlation between the second modulated optical signal and the second return optical signal;
wherein the apparatus further comprises a first network node, a second network node, and a fiber-optic cable;
wherein the first network node includes the first transceiver, the second transceiver, and the optical multiplexer;
wherein the second network node includes a third transceiver configured to generate a third modulated optical signal having a respective carrier wavelength;
wherein the second network node is configured to:
generate a third WDM signal that includes the third modulated optical signal as a WDM component thereof;
apply the third WDM signal to a second optical link;
receive back from the second optical link a fourth WDM signal;
and
demultiplex the fourth WDM signal to generate a third return optical signal;
wherein the third transceiver is further configured to determine a third correlation between the third modulated optical signal and the third return optical signal;
and
wherein the fiber-optic cable includes a first optical fiber and a second optical fiber, the first optical fiber being a part of the first optical link that transmits the first WDM signal, and the second optical fiber being a part of the second optical link that transmits the third WDM signal.

17 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/198,532Filed 30 Jun 2016
Published: US 2018/0006722 A14 Jan 2018
Granted: 1 May 2018
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H04L 5/0044
Arrangements for allocating sub-channels of the transmission path: allocation of payload; Allocation of data channels, e.g. PDSCH or PUSCH
H04B 10/071
Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems: using a reflected signal,…
H04J 14/0256
Optical medium access: at the optical channel layer
H04L 5/0008
The frequencies being orthogonal, e.g. OFDM or DMT: wavelet-division