Exfo Inc.

Exfo Oy

Daniel Gariepy

Gang He

Bernard Ruchet

Mario L'Heureux

Etienne Morin-Drouin

Yves Breton

Stephane Perron

Robert Baribault

Normand Cyr

Mats Skold

Hongxin Chen

Nicolas Caron

Sakari Yrttiaho

Vincent Racine

Vesa Kyllönen

There is herein provided a method for measuring the GOSNR that can be implemented using commercial-grade transceivers and which accounts for linear optical impairments (e.g. PMD, PDL and CD) and transceiver intrinsic impairments. The method may be implemented using an Optical Spectrum Analyzer (OSA) and either the system transceivers or other commercial-grade transceivers. The proposed measurement method is based on mixed optical and electronic technologies, using an OSA and a transceiver pair. By measuring a signal quality metric Qand the OSNR under varied power and ASE noise conditions, a constant value Rthat relates the GOSNR to the signal quality metric Qis derived. The GOSNR is then obtained from these results.

Transceiver agnostic GOSNR measurement

There is provided a system and a method for extracting data traffic from an optical communication fiber by extracting a portion of the optical signal(s) propagating in the optical communication fiber, carrying the extracted signal over an optical fiber, amplifying the extracted optical signal and filtering the amplified signal to select one channel carrying data traffic. The optically-carried data traffic may then be input to an optical communication transceiver for converting the optically-carried data traffic into electrical data traffic, which carried data can be analyzed for data traffic monitoring applications.

Extracting data traffic from an optical communication fiber

There is provided a method, system and image capture device for determining a polarity of a multi-fiber cable link comprising a plurality of optical fiber links each connected between a first multi-fiber connector and a second multi-fiber connector, according to said polarity. Test light is injected into one or more of the optical fiber links via corresponding injection ports of the first multi-fiber connector, in accordance with a defined injection pattern; at least one polarity-testing image of the second multi-fiber connector is generated in which test light exiting at least one of the optical fiber links through one or more exit ports of the second multi-fiber connector is imaged as one or more spotlight spots in the polarity-testing image; and the polarity of the multi-fiber cable link is determined based on a pattern of said one or more spotlight spots in said polarity-testing image.

Method and system for multi-fiber cable testing

A device and method for optical power measurement in an optical network supporting upstream and downstream signal propagation along an optical transmission path. An upstream wavelength analyzer receives upstream light extracted from the optical transmission path and is configured to determine an upstream spectral characteristic of the extracted upstream light. A downstream optical power meter assembly receives downstream light extracted from the optical transmission path and is configured to measure an optical power parameter of a downstream signal. A processing unit is configured to determine, based on the upstream spectral characteristic, at least one pass/fail threshold associated with the measured optical power parameter of the downstream signal.

Optical power measurement in a passive optical network

A device and method for optical power measurement in an optical network supporting upstream and downstream signal propagation along an optical transmission path. The device includes an upstream wavelength analyzer receiving upstream light extracted from the optical transmission path and configured to determine an upstream spectral characteristic of the extracted upstream light. The device also includes a downstream filter assembly receiving downstream light extracted from the optical transmission path and configured to spectrally split the extracted downstream light into a plurality of downstream signals, one of which corresponding to a downstream signal of interest. The device further includes a processing unit configured to identify, based on the upstream spectral characteristic, the downstream signal of interest among the downstream filtered signals, and a downstream optical power meter assembly coupled to the downstream filter assembly and configured to measure an optical power parameter of the downstream signal of interest.

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.

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

There are provided methods and devices for determining a quality parameter characterizing an optical communication signal, the methods being performed by signal detection devices. At the transmitting end, there are obtained a signal power Pof a first optical signal, a signal power Pof a second optical signal, a signal power Pof a third optical signal, optionally a signal power Pof a fourth optical signal, and a total signal power Ps of a channel where the first, second, third and optional fourth optical signals are located. At a detection point, there are further obtained a signal power P' of the first optical signal, a signal power P&#x2032; of the second optical signal, a signal power P&#x2032; of the third optical signal and optionally a signal power P&#x2032; of the fourth optical signal. There are then determined a signal deformation factor SDF and/or an optical signal to ASE noise ratio OSNR from the obtained signal powers.

In-band noise determination on optical communication signals

A passive optical network (PON) device and method for optical power measurement along an optical transmission path supporting bidirectional propagation of downstream light and upstream light between two network elements of a PON is provided. The device includes an optical power splitter assembly extracting respective portions of the upstream and downstream light, and an upstream wavelength analyzer determining, from the extracted upstream light, an upstream spectral characteristic of the upstream light. The device also includes a processing unit determining, based on the upstream spectral characteristic, a downstream spectral characteristic of a downstream signal of interest among a plurality of downstream signals of the downstream light, and a downstream filter assembly filtering the extracted downstream light to select a portion of the downstream signal of interest. The device further includes a downstream optical power meter assembly measuring an optical power parameter of the selected portion of the downstream signal of interest.

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.

Characterization of linear crosstalk on multiplexed optical signals

There is provided a method and an apparatus for determining quality parameters on a polarization-multiplexed optical signal based on an analysis of the power spectral density of the Signal-Under-Test (SUT). The method is predicated upon knowledge of the spectral shape of the signal in the absence of significant noise or spectral deformation. This knowledge is provided by a reference optical spectrum trace. Based on this knowledge and under the assumption that ASE noise level is approximately constant in wavelength over a given spectral range, the spectral deformation of the signal contribution of the SUT may be estimated using a comparison of the spectral variations of the optical spectrum trace of the SUT with that of the reference optical spectrum trace.

Signal deformation measurement on polarization-multiplexed signals

There is provided a method for determining a noise parameter characterizing an optical Signal-Under-Test (SUT) having a signal contribution, an Amplified Spontaneous Emission (ASE) noise contribution and a non-ASE optical noise contribution, such as a carrier-leakage contribution or a depolarized-signal contribution, within an optical-signal bandwidth. The method comprises acquiring optical spectrum trace(s) of the SUT, discriminating at least the non-ASE optical noise contribution from the ASE-noise contribution using the optical spectrum trace(s) and/or a trace obtained from the optical spectrum trace(s); and determining the noise parameter using discriminated non-ASE optical noise contribution and/or the discriminated ASE-noise contribution.

Characterization of non-ASE noise on optical signals

There is provided a method for determining an in-band noise parameter, such as the Optical Signal-to-Noise Ratio (OSNR), on an optical signal-under-test (SUT) propagating along an optical communication link and comprising a data-carrying signal contribution of any arbitrary degree of polarization and a noise contribution. A spectral shape trace of data-carrying signal contribution in the SUT is estimated using a reference optical spectrum trace of a reference signal which comprises a data-carrying signal contribution that is spectrally representative of the data-carrying signal contribution of the SUT and a noise contribution which is at least approximately known. The data-carrying signal contribution is mathematically discriminated from said noise contribution in the SUT using the spectral shape trace and the test optical spectrum trace. The in-band noise parameter is then determined at least from the mathematically discriminated noise contribution.

Reference-based in-band OSNR measurement on polarization-multiplexed signals

There is provided a method for determining the in-band noise in agile multichannel Dense Wavelength Division Multiplexing (DWDM) optical systems, where the interchannel noise is not representative of the in-band noise in the optical channel. The method relies on the analysis of two observations of the same input optical signal. In the two observations, the linear relationship between the optical signal contribution and the optical noise contribution (e.g. the observed OSNR) is different, which allows the discrimination of the signal and noise contributions in the input optical signal. In a first approach, the two observations are provided by polarization analysis of the input optical signal. In a second, the input optical signal is obtained using two different integration widths.

Method and system for determining in-band optical noise

A method comprises: acquiring, for a number nSOP of varied State-Of-Polarization analysis conditions of the input optical signal, nSOP polarization-analyzed optical spectrum traces; mathematically discriminating said signal contribution from said noise contribution within said optical signal bandwidth using said polarization-analyzed optical spectrum traces, said mathematically discriminating comprising: obtaining a differential polarization response that is related to the optical spectrum of said signal contribution by a constant of proportionality; estimating the constant of proportionality of a differential polarization response to the optical spectrum of said signal contribution; estimating the optical spectrum of said noise contribution from said input optical signal, within said optical signal bandwidth using said constant of proportionality and said differential polarization response; and determining said in-band noise parameter on said input optical signal from the mathematically discriminated noise contribution.

In-band optical noise measurement using differential polarization response

There is provided a method for determining the in-band noise in agile multichannel Dense Wavelength Division Multiplexing (DWDM) optical systems, where the interchannel noise is not representative of the in-band noise in the optical channel. The method relies on the analysis of two observations of the same input optical signal. In the two observations, the linear relationship between the optical signal contribution and the optical noise contribution (i.e. the observed OSNR) is different, which allows the discrimination of the signal and noise contributions in the input optical signal. In a first approach, the two observations are provided by polarization analysis of the input optical signal. In a second, the input optical signal is obtained using two different integration widths.

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Daniel Gariepy