In-band noise and/or spectral deformation measurement on polarization-multiplexed signals

Patent metadata

Field	Value
Publication number	US-10128975-B2
Application number	US-201514931983-A
Country	US
Kind code	B2
Filing date	Nov 4, 2015
Priority date	Nov 5, 2014
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

There is provided a method to discriminate NLE-induced signal deformation from ASE-noise on polarization multiplexed signals, in order to measure the OSNR under NLE conditions and/or characterize the NLE-induced signal deformation. In accordance with one aspect, the method is based on the acquisition of optical spectrum traces when the (data-carrying) optical communication signal is partially or completely extinguished (ASE-noise only), as well as with a live optical communication signal. Comparing traces acquired with different conditions and/or at different dates allows discrimination of the signal contribution, the ASE-noise contribution and the NLE-induced deformations on the SUT.

First claim

What is claimed is:

1. A method for characterizing an optical signal-under-test (SUT) resulting from the propagation of a polarization-multiplexed optical signal on an optical communication link subject to non-linear effects and optical add/drop multiplexing, the SUT comprising at least a data-carrying signal contribution and an Amplified Spontaneous Emission (ASE) noise contribution N ASE _ SUT within an optical signal bandwidth, the method comprising:
at a test point on said optical communication link and at a first time period:
while the polarization-multiplexed optical signal on said optical communication link is live within said optical signal bandwidth, acquiring, using a test instrument, a first commissioning optical spectrum trace P Rx _ t1 _ L (λ) of said polarization-multiplexed optical signal, said first optical spectrum trace extending over a spectral range encompassing at least a portion of said optical signal bandwidth;
while the polarization-multiplexed optical signal on said optical communication link is extinguished within said optical signal bandwidth, acquiring, using a test instrument, a second commissioning optical spectrum trace P Rx _ t1 _ E (λ) extending over a spectral range encompassing at least said portion of said optical signal bandwidth;

at said test point on said optical communication link and at a second time period:
acquiring, using a test instrument, a test optical spectrum trace P SUT (λ) of said SUT, said test optical spectrum trace extending over a spectral range encompassing at least said portion of said optical signal bandwidth;

using a processing module,
deriving, from said second commissioning optical spectrum trace P Rx _ t1 _ E (λ), a first ASE-noise level N ASE _ Rx _ t1 (λ) on said first commissioning optical spectrum trace P Rx _ t1 _ L (λ);
determining a first spectral shape trace S Rx _ t1 (λ) of said data-carrying signal contribution of said polarization-multiplexed optical signal at said first time period and at said test point using at least said first commissioning optical spectrum trace P Rx _ t1 _ L (λ) and said first ASE-noise level N ASE _ Rx _ t1 (λ) using a relation equivalent to the following equation:
S Rx _ t1 (λ)= P Rx _ t1 _ L (λ)− N ASE _ Rx _ t1 (λ);

determining, within said spectral range, a relative signal deformation k(λ) of the data-carrying signal contribution between said optical signal at said first time period and said SUT at said second time, using a relation equivalent to the following relation:

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Assignees

• Exfo Inc

Inventors

• He Gang
• Gariepy Daniel

Classifications

• H04B10/0795 Primary

  Performance monitoring; Measurement of transmission parameters · CPC title

• H04B10/0775

  Performance monitoring and measurement of transmission parameters · CPC title

• H04J14/06 Primary

  Polarisation multiplex systems · CPC title

• H04B10/07953 Primary

  Monitoring or measuring OSNR, BER or Q · CPC title