Analytical Expressions for Nonlinear Transmission Performance of Coherent Optical OFDM Systems With Frequency Guard Band

Closed-form expressions for nonlinear transmission performance of coherent optical OFDM systems (CO-OFDM) with frequency guard band are derived. The analytical expressions have been substantiated by numerical simulations using split-step method for various frequency spacings and fiber dispersion maps. The analytical solution shows good estimation accuracy, and the average absolute difference of Q factor between analytical results and numerical simulations are below 0.3 dB for the three typical systems simulated. Using this expression, the dependence of system performance for CO-OFDM on the frequency guard band spacing and fiber dispersion is also investigated analytically to provide insights for system design.