Impact of ASE noise in WDM systems

The small signal analysis method is presented for the discussion of amplified spontaneous emission (ASE) noise in dispersion and nonlinear transmission fibers in wavelength division multiplex (WDM) systems. Based on it, the complete ASE noise spectra (include the ASE noise, the ASE noise enhanced by parametric gain and the crosstalk caused by ASE noise and parametric gain) are described and the factors impacting on them are discussed. The crosstalk caused by ASE noise and parametric gain in single mode fibers, non-zero dispersion shift fibers and dispersion compensation fibers are analyzed. Taking into account the dispersion effect in the transmission fibers, the three types of ASE noise may decrease.