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Method and system for determining in-band optical noise

A technology with in-bandwidth and noise components, applied in transmission systems, electromagnetic wave transmission systems, transmission monitoring/testing/fault measurement systems, etc., can solve problems such as increasing modulation rate and difficulty in reliable measurement

Active Publication Date: 2014-02-19
EXFO
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, increased modulation rates, combined with narrow filtering in multiplexers and demultiplexers, make it increasingly difficult to achieve reliable measurements of noise levels within the channel bandwidth

Method used

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  • Method and system for determining in-band optical noise
  • Method and system for determining in-band optical noise
  • Method and system for determining in-band optical noise

Examples

Experimental program
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Embodiment 1

[0072] will now refer to Figure 7 , describing an example implementation of the processing performed by the spectral processor 18 in order to discriminate between the signal component S and the noise component N.

[0073] In the following, the spectral traces are analyzed and processed in the spectral neighborhood of the DWDM optical channel or each signal peak included into the input optical signal for which the in-band noise level is to be determined. Signal peaks are identified using standard known implementation techniques to determine their respective center wavelengths (λ p ). The in-band noise level and OSNR on each signal peak can be estimated using the methods described herein without requiring the acquisition of other further spectral traces.

[0074] In step 502, different polarization analysis conditions are used as described above, and in this case generally Figure 6 The polarizer 34 generates two samples p from the input optical signal p A and p B . In st...

Embodiment 2

[0138] now refer to Figure 10 and Figure 11 , describing an example implementation of a method according to the DRBD method.

[0139] In this example, the numerical integration function h 1 (λ) and h 2 (λ) are respectively with width RBW 1 and RBW 2 The rectangular convolution window of . In step 1002, two spectral traces P are obtained by first obtaining an input spectral trace 1 (λ) and P 2 (λ):

[0140] P(λ)=h OSA (λ)*p(λ)=S(λ)+N(λ), (29)

[0141] Then with the convolution window h 1 (λ) and h 2 (λ) and integrate it to obtain P 1 (λ) and P 2 (λ) (see equations (25) and (26), where in this example h OSA (λ)=h OSA1 (λ)=h OSA2 (λ)). use h 1 (λ) Obtain two spectral traces P 1 (λ) and P 2 (λ), select h 1 (λ), so that in the immediate vicinity of the peak, that is, at λ p ±δλ (where δλ is greater than the acquisition resolution), S 1 The signal peak formed in (λ) is flat (eg Figure 11 shown), or S 1 The signal peak in (λ) exhibits a constant slope, ie ...

Embodiment 3

[0155] When the signal peak is almost as wide as the width of the noise component in the optical channel, Figure 10 Assumptions made in the method - at wider bandwidth RBW 2 The signal peak power integrated on is equal to when the RBW 1 Signal peak power integrated on - becomes unsuitable. However, when the spectral shape of the signal components is known, it is no longer necessary to select the first convolution window h that includes the full signal power 1 (λ). For example, the spectral shape of the signal component s(λ) can be derived by identifying the modulation spectrum of the signal, or dependent on the polarization properties as described above, which would be an embodiment of a hybrid approach as described below. The spectral shape of the signal component s(λ) can also be obtained by applying filtering techniques—assuming that the noise component n(λ) changes spectrally more slowly than the signal component s(λ) above the bandwidth of the optical signal. Compone...

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Abstract

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.

Description

technical field [0001] The present invention relates to the determination of in-band noise in optical telecommunications applications. More specifically, the present invention relates to the determination of in-band noise in dense wavelength division multiplexed (DWDM) optical networks. Background technique [0002] The IEC 61280-2-9 Optical Fiber - Optical Communication Subsystem Test Procedures - Part 2-9 standard (version 1.0b:2002) provides a standard method for determining OSNR in DWDM networks. The method is based on the assumption that the inter-channel noise level represents the noise level at the signal peak location. This method interpolates the power level of the noise outside the signal bandwidth to calculate the in-band noise within the signal bandwidth. The increased modulation rate expands the signal bandwidth, while the increased channel density reduces the inter-channel width, thereby placing stringent requirements on the spectral characteristics of the sp...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B10/07
CPCH04B10/07953
Inventor D·加里皮何刚Y·布雷顿
Owner EXFO