optic.models.perturbation.perturbationNLIN

perturbationNLIN(Ein, param)

Calculates the intrachannel NLIN via first-order perturbation models.

Parameters:

  • Ein (ndarray of shape (N, 2)) – Input signal for dual-polarization (complex-valued). The first column represents the X polarization, and the second column represents the Y polarization.

  • param (optic.utils.parameters object) –

    Object with physical/simulation parameters of the optical channel.

    • param.D : chromatic dispersion parameter [ps/nm/km] [default: 17 ps/nm/km]

    • param.alpha : fiber attenuation parameter [dB/km] [default: 0.2 dB/km]

    • param.lspan : span length [km] [default: 50 km]

    • param.length : total fiber length [km] [default: 800 km]

    • param.pulseWidth : pulse width (fraction of symbol period) [default: 0.5]

    • param.gamma : fiber nonlinear coefficient [1/W/km] [default: 1.3 1/W/km]

    • param.Fc : carrier frequency [THz] [default: 193.2e12 Hz]

    • param.powerWeighted : power-weighted coefficient calculation? Boolean variable [default: False]

    • param.Rs : symbol rate [baud] [default: 32e9 baud]

    • param.powerWeightN : power-weighting order [default: 10]

    • param.matrixOrder : nonlinear memory matrix order [default: 25]

    • param.mode : ‘AM’ for standard perturbation calculation or ‘AMR’ for reduced complexity calculation [default: ‘AM’]

    • param.Pin : launch power per channel [dBm] [default: 0 dBm]

    • param.coeffTol : threshold for ignoring small perturbation coefficients [dB] [default: -20 dB]

    • param.prec : numerical precision [default: np.complex128]

Returns:

nlin – Nonlinear perturbation for dual-polarization signals. The first column represents the X polarization, and the second column represents the Y polarization.

Return type:

ndarray of shape (N, 2)

References

[1] Z. Tao, et al., “Analytical Intrachannel Nonlinear Models to Predict the Nonlinear Noise Waveform,” Journal of Lightwave Technology, vol. 33, no. 10, pp. 2111-2119, 2015.

[2] E. P. da Silva, et al., “Perturbation-Based FEC-Assisted Iterative Nonlinearity Compensation for WDM Systems,” Journal of Lightwave Technology, vol. 37, no. 3, pp. 875-881, 2019.