Performance limitations due to combined influence of ASE and Raman amplifier induced crosstalk in a WDM system with direct detection receiver

An analytical approach is presented to evaluate the bit error rate performance of a wavelength division multiplexing (WDM) fiber-optic transmission link with distributed Raman amplifier taking into account the combined effect of Amplified Spontaneous Emission (ASE) and Raman scattering induced crosstalk for direct detection receiver. The analysis is developed to find the photodetector output due to Raman scattering and ASE noise. The signal to noise plus crosstalk ratio at the receiver output is derived. The bit error rate (BER) performance results are numerically evaluated for 10 Gbps and different fiber length and WDM channels. It is found that at a BER of 10
^-9
, the allowable transmission distance is limited by ASE and crosstalk due to Raman scattering. The maximum allowable pump power is 1 mW, 3 mW, 4 mW, 6 mW for channel bandwidth 100 GHz, 50 GHz, 25 GHz and 12.5 GHz respectively for fiber length of 50 Km at BER 10
^-9
. The effect of ASE is more prominent at higher pump power