Digital Back Propagation

class DBP(N_spans: int = 1, L_span: float = 80, StPS: int = 1, fs: float = 1, step_type: Literal['linear', 'logarithmic'] = 'linear', step_method: Literal['symmetric', 'asymetric'] = 'symmetric', use_only_linear: bool = False, c: float = 299792458, h: float = 6.62607015e-34, gamma: float = 1.3, lamb: float = 1550, alpha_dB: float = 0.2, cd_coefficient: float = 17, nu: float = 193414489032258.06, step_log_factor: float = 0.4, name: str = 'dbp')

A class that implements Digital Back Propagation (DBP).

This class extends FiberLink and is used for simulating the process of digital back propagation in optical fiber communication systems. DBP compensates for signal distortions such as chromatic dispersion and Kerr nonlinearity effects.

Attributes

N_spansint

Number of spans in the fiber link.

L_spanfloat

Length of each span in kilometers.

StPSint

Steps per span.

fsfloat

Sampling frequency in Hz.

step_typeLiteral[“linear”, “logarithmic”]

Type of step size (‘linear’ or ‘logarithmic’).

step_methodLiteral[“symmetric”, “asymetric”]

Method for splitting steps (‘symmetric’ or ‘asymetric’).

use_only_linearbool

Flag to consider only linear effects.

namestr

Name of the span.

cfloat

Speed of light in meters per second.

hfloat

Planck constant in Joule seconds.

gammafloat

Kerr coefficient in rad/W/km.

lambfloat

Wavelength in nanometers.

alpha_dBfloat

Fiber loss in dB/km.

cd_coefficientfloat

Chromatic dispersion coefficient in ps/nm/km.

nufloat

Optical carrier frequency.

step_log_factorfloat

Logarithmic step factor.

gainfloat

Gain factor calculated based on attenuation coefficient and span length.

Notes

The DBP class is used in combination with other classes from the comnumpy package to simulate an optical communication system. It specifically addresses the digital compensation of signal impairments due to fiber transmission.

References

• [1] O. V. Sinkin, R. Holzlohner, J. Zweck and C. R. Menyuk, “Optimization of the split-step Fourier method in modeling optical-fiber communications systems,” in Journal of Lightwave Technology, vol. 21, no. 1, pp. 61-68, Jan. 2003, doi: 10.1109/JLT.2003.808628.