Negative Power Penalties of Optical OFDM Signal Transmissions in Directly Modulated DFB Laser-Based IMDD Systems Incorporating Negative Dispersion Fibers

Detailed investigations of dynamic negative power penalty characteristics of optical orthogonal frequency division multiplexing (OOFDM) signal transmissions are undertaken, for the first time, in directly modulated distributed feedback (DFB) laser (DML)-based intensity modulation and direct detection (IMDD) systems incorporating negative dispersion fibers such as MetroCor fibers. Excellent agreements between numerical simulations and real-time experimental measurements are obtained over a wide diversity of transmission conditions of the aforementioned systems. The physical mechanism underpinning the occurrence of negative power penalties is the reduction in subcarrier intermixing impairment due to the compensation between DML positive frequency chirps and MetroCor negative chromatic dispersions. It is also shown that the negative power penalty is independent of both cyclic prefix and signal modulation format and, more importantly, controllable when adaptive modulation and/or appropriate adjustments of DML operating conditions are applied.