Characterization of linear crosstalk on multiplexed optical signals

Patent metadata

Field	Value
Publication number	US-9673894-B2
Application number	US-201214009236-A
Country	US
Kind code	B2
Filing date	May 28, 2012
Priority date	May 27, 2011
Publication date	Jun 6, 2017
Grant date	Jun 6, 2017

Abstract

There is provided a method of determining at least one linear-crosstalk-related parameter of an optical signal-under-test having, within an optical channel bandwidth, at least a data-carrying signal contribution and a wavelength-dependent linear-crosstalk contribution arising from a data-carrying signal contribution of an adjacent optical signal associated with an adjacent channel to the optical signal-under-test, the method comprising: acquiring at least one optical spectrum trace encompassing a quasi-continuum of closely-spaced wavelengths over a spectral range extending to at least part of both the signal under test and the adjacent optical signal; and estimating said linear-crosstalk contribution using at least spectral properties of said at least one optical spectrum trace; wherein one of said at least one linear-crosstalk-related parameter is the linear-crosstalk contribution and is determined from said estimating.

First claim

What is claimed is:

1. A method of determining at least one linear-crosstalk-related parameter of an optical signal-under-test having, within an optical channel bandwidth, at least a data-carrying signal contribution and a wavelength-dependent linear-crosstalk contribution arising from a data-carrying signal contribution of an adjacent optical signal associated with an adjacent channel to the optical signal-under-test, the method comprising:
using an optical spectrum analyzer, acquiring at least one optical spectrum trace encompassing a quasi-continuum of closely-spaced wavelengths over a spectral range extending to at least part of both the signal under test and the adjacent optical signal, wherein both of said signal-under-test and said adjacent optical signal are non-polarization-multiplexed, said acquiring comprises
acquiring said at least one optical spectrum trace in a polarization-analyzed manner for each of a number n SOP of at least two different state-of-polarization analysis conditions; and
determining at least one extrema trace from said at least two polarization-analyzed optical spectrum traces;

using a processor,
determining a data-carrying signal contribution of said adjacent optical signal at at least some wavelength values within said adjacent channel using at least one of said at least one optical spectrum trace;
extrapolating the determined data-carrying signal contribution within a portion of the optical channel bandwidth that corresponds to at least a portion of the spectral range;
estimating said linear-crosstalk contribution based on the extrapolated data-carrying signal contribution of said adjacent optical signal, wherein said estimating said linear-crosstalk contribution comprises using at least spectral properties of said at least one extrema trace;

wherein said at least one linear-crosstalk-related parameter is determined at least from the estimated linear-crosstalk contribution, further comprising estimating an interchannel relative state-of-polarization between said data-carrying signal contribution of said adjacent optical signal and said data-carrying signal contribution of said signal-under-test, wherein a further one of said at least one linear crosstalk-related parameter is the interchannel relative state-of-polarization.

2. The method as claimed in claim 1 , wherein said determining said data-carrying signal contribution of said adjacent optical signal includes estimating said data-carrying signal contribution assuming a negligible amplified spontaneous noise contribution.

3. The method as claimed in claim 1 , wherein said extrapolating comprises:
identifying a region of the optical spectrum trace having at least two wavelengths on the adjacent optical signal, the region being linear when represented a logarithmic scale, and
calculating an adjacent signal projection of the linear region into the optical channel bandwidth of the signal-under-test, said projection being linear when represented on the logarithmic scale.

4. The method as claimed in claim 3 , wherein said extrapolating further comprises:
identifying a region of the optical spectrum trace having at least two wavelengths on the optical signal-under-test, the region being linear when represented on the logarithmic scale,
calculating a signal-under-test projection of the linear region of the optical signal-under-test into the adjacent channel, said adjacent projection being linear when represented on the logarithmic scale, and
refining said adjacent signal projection using said calculated signal-under-test projection.

5. The method as claimed in claim 1 further comprising determining another one of said at least one linear crosstalk-related parameter using the estimated relative state-of-polarization.

6. The method as claimed in claim 5 , wherein said linear-crosstalk-related parameter comprises a parallel Optical Signal-to-Crosstalk Ratio.

7. The method as claimed in claim 1 , wherein said estimating an interchannel relative state-of-polarization includes using at least said at least one extrema trace.

8. A method of determining at least one linear-crosstalk-related parameter of an optical signal-under-test having, within an optical channel bandwidth, at least a data-carrying signal contribution and a wavelength-dependent linear-crosstalk contribution arising from a data-carrying signal contribution of an adjacent optical signal associated with an adjacent channel to the optical signal-under-test, the method comprising:
using an optical spectrum analyzer, acquiring at least one optical spectrum trace encompassing a quasi-continuum of closely-spaced wavelengths over a spectral range extending to at least part of both the signal under test and the adjacent optical signal, wherein both of said signal-under-test and said adjacent optical signal are non-polarization-multiplexed, said acquiring comprises:
acquiring said at least one optical spectrum trace in a polarization-analyzed manner for each of a number nSOP of at least two different state-of-polarization analysis conditions; and
determining at least one extrema trace from said at least two polarization-analyzed optical spectrum traces;

using a processor,
determining a data-carrying signal contribution of said adjacent optical signal at at least some wavelength values within said adjacent channel using at least one of said at least one optical spectrum trace;
extrapolating the determined data-carrying signal contribution within a portion of the optical channel bandwidth that corresponds to at least a portion of the spectral range;
estimating said linear-crosstalk contribution based on the extrapolated data-carrying signal contribution of said adjacent optical signal, wherein said estimating said linear-crosstalk contribution comprises using at least spectral properties of said at least one extrema trace;

wherein said at least one linear-crosstalk-related parameter is determined at least from the estimated linear-crosstalk contribution, further comprising,
for one acquired optical spectrum trace:
determining, within said spectral range, a minimum value,
obtaining an estimated ASE noise contribution,
obtaining a power value by removing from the minimum value the estimated ASE noise contribution,

for one of said extrema trace
determining, within said spectral range, a minimum value,
obtaining an estimated ASE noise contribution,
obtaining a power value by removing from the minimum value the estimated ASE noise contribution, and

determining a relative state of polarization parameter by comparing the power value obtained for the optical spectrum trace with the power value obtained for the extrema trace.

9. A method of determining at least one linear-crosstalk-related parameter of an optical signal-under-test having, within an optical channel bandwidth, at least a data-carrying signal contribution and a wavelength-dependent linear-crosstalk contribution arising from a data-carrying signal contribution of an adjacent optical signal associated with an adjacent channel to the optical signal-under-test, the method comprising:
using an optical spectrum analyzer, acquiring at least one optical spectrum trace encompassing a quasi-continuum of closely-spaced wavelengths over a spectral range extending to at least part of both the signal under test and the adjacent optical signal, wherein both of said signal-under-test and said adjacent optical signal are non-polarization-multiplexed, said acquiring comprises:
acquiring said at least one optical spectrum trace in a polarization-analyzed manner for each of a number nSOP of at least two different state-of-polarization analysis conditions; and
determining at least one extrema trace from said at least two polarizat

Assignees

• Gariepy Daniel
• He Gang
• Exfo Inc

Inventors

• Gariepy Daniel
• He Gang

Classifications

• H04B10/07 Primary

  Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems · CPC title

• H04B2210/07

  Monitoring an optical transmission system using a supervisory signal · CPC title

• H04B10/0795 Primary

  Performance monitoring; Measurement of transmission parameters · CPC title