Beijing Institute of Technology

Aiying Yang

Xiaoyu Chen

The present invention relates to a method of measuring optical fiber link chromatic dispersion by fractional Fourier transformation (FRFT), belonging to the technical field of optical communication. The method of the present invention performs coherent demodulation for an optical pulse signal output from the optical fiber link to obtain a complex field of the optical pulse signal, then performs FRFT on the complex field; according to the energy focusing effect of the chirp signal in the fractional spectrum, calculates an optimal fractional order of the FRFT, and then calculates chromatic dispersion of the optical fiber link according to the optimal fractional order. The method can be applied to an optical fiber communication system consisting of different types of optical fibers, to perform monitoring of optical fiber link chromatic dispersion.

Method of measuring optical fiber link chromatic dispersion by fractional Fourier transformation (FRFT)

The present invention proposes a method for monitoring the nonlinear effect of an optical fiber link by fractional Fourier transformation, FRFT, by calculating an optimal fractional order of the FRFT of the frequency-domain signal propagating through an optical fiber link, calculating the chromatic dispersion of an optical fiber link based on the optimal fractional order, compensating for chromatic dispersion to the signal, calculating an optimal fractional order of the FRFT for the time-domain signal following the compensation for chromatic dispersion, calculating the time-domain chirp caused by the nonlinear effect of an optical fiber link based on the optimal fractional order, and monitoring the nonlinear effect of an optical fiber link based on the absolute value of the calculated time-domain chirp. The method can be used for quantitatively monitoring the nonlinear effect of an optical fiber link in an optical fiber communication system consisting of different types of optical fibers.

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Beijing, China

Aiying Yang