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Method and apparatus for detection and compensation of PMD parameters in signals transmitted over optical fiber links and system of communication therewith

A polarization mode dispersion, compensator technology, applied in the field of communication systems, can solve problems such as unsatisfactory

Inactive Publication Date: 2008-10-01
TELEFON AB LM ERICSSON (PUBL)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the case of modern communication systems with channels of very wide bandwidth (e.g. 7 to 20 GHz for 10Gbit / s systems and 30 to 60 GHz for 40Gbit / s systems), it is even known over the entire bandwidth of the signal channel The system also does not give satisfactory results

Method used

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  • Method and apparatus for detection and compensation of PMD parameters in signals transmitted over optical fiber links and system of communication therewith
  • Method and apparatus for detection and compensation of PMD parameters in signals transmitted over optical fiber links and system of communication therewith
  • Method and apparatus for detection and compensation of PMD parameters in signals transmitted over optical fiber links and system of communication therewith

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Embodiment Construction

[0013] Referring to FIG. 1 , FIG. 1 shows the structure of a communication system provided according to the present invention, and the whole system is indicated by reference numeral 10 . The communication system comprises a transmission system 11 that sends signals to a receiver 13 via a fiber optic based link 12 . The transmission system can be one channel or multiple channels, preferably WDM type, because it is easy to imagine for those skilled in the art, so it will not be illustrated and described in detail here. Such systems usually work at a rate not lower than 2.5Gbit / s. The signal frequency band is correspondingly high (7 to 20 GHz at 10 Gbit / s and 30 to 60 GHz at 40 Gbit / s). The signal format can be various, such as NRZ, RZ, CRZ, solitary wave and so on.

[0014] A known PMD compensator 14 may be arranged along the signal path, for example of the type comprising birefringent elements and polarization transforming means (ie rotators and / or polarization controllers). ...

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Abstract

A method of detecting polarization mode dispersion (PMD) indicative parameters of an optical fiber link comprising at least one transmission channel in which is transmitted a first wideband optical signal with a bandwidth divided into sub-bands. For each sub-band is produced a second reference optical signal with which to find a third optical signal by superposition. For each of the third signals are calculated first parameters considered indicative of the PMD thereof, and with the first parameters of all the sub-bands are calculated second parameters considered indicative of the PMD of the first wideband signal. The method can be used as part of a PMD compensation method for a transmission system employing the parameters calculated for feedback piloting of a PMD compensator. A detection apparatus comprises a generator for generation of the second reference optical signals, an optical mixer for producing superimposition of the first and second signals, one or more photodetectors for finding the electrical beat signal or the first and second signals, a calculation device for calculating the first parameters, and a processor for processing all the first parameters to find therefrom the second parameters which will then be furthered processed. The detection apparatus can be part of a compensation apparatus comprising the compensator and a calculation stage for calculating the compensation and piloting the compensator. The entirety can be part of an optical fiber communication system.

Description

technical field [0001] The present invention relates to methods and apparatus for the detection and, where necessary, compensation of polarization mode dispersion (PMD) that occurs when optical signals propagate over optical fiber-based links. The invention also relates to a communication system using the above method and device. Background technique [0002] PMD is known to cause distortion and dispersion of optical signals sent over fiber optic links. The combined effect is to distort and disperse the optical signal. The different time delays of various components in the signal under various polarization states become more important as the transmission speed increases. In modern optical fiber-based transmission systems at higher digital frequencies (10Gbit / s and higher), accurate measurement and compensation of PMD effects is very important. [0003] In the prior art, some methods and devices for PMD measurement and compensation have been proposed to improve the quality...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04B10/18H04B10/2569
CPCH04B10/2569
Inventor A·加尔塔罗萨L·帕尔米里R·费奥罗尼A·科尔蒂
Owner TELEFON AB LM ERICSSON (PUBL)
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