Modeling of bit error rate in cascaded 2R regenerators

This paper presents a simple and efficient model for estimating the bit error rate (BER) in a cascade of optical reamplification and reshaping (2R) regenerators. The model includes the influences of amplifier noise, finite extinction ratio (ER), and nonlinear reshaping. The interplay between the different signal impairments and the regenerating nonlinearity is investigated. It is shown that an increase in nonlinearity can compensate for an increase in noise figure or decrease in signal power. Furthermore, the influence of the improvement in signal ER along the cascade and the importance of choosing the proper threshold of the nonlinearity are investigated.