Digital Back Propagation With Optimal Step Size for Polarization Multiplexed Transmission

A digital back propagation (DBP) scheme with optimal step size for polarization division multiplexed transmission system is proposed. For a fixed number of steps in DBP, the optimum step size is calculated by minimizing the mismatch between the area under the exponentially increasing nonlinearity profile and its stepwise approximation. In simulations, the vector nonlinear Schodinger equation or Manakov equations are used for forward propagation and Manakov equations are used for backward propagation. The simulation results show that the proposed scheme using the optimum step size outperforms that using the uniform step size at the same computational cost.