The transmission performance of carrier-suppressed, single-sideband (SSB), optical orthogonal frequency division multiplexing (OOFDM) signals is investigated numerically in intensity-modulation and direct-detection (IMDD) single-mode fiber (SMF) systems using directly modulated DFB lasers (DMLs), with special attention being given to the impact of DMLs on the system performance. The dependence of the optimum carrier suppression ratio is identified on DML operating condition and optical input power. It is shown that, for DML-based optical amplification-free metropolitan systems, 30 Gb/s over 80-km SMF transmission is achievable, which doubles the performance obtained by using double-sideband (DSB) OOFDM signals without carrier suppression, and that 10 Gb/s over 1200-km SMF transmission is also feasible for DML-based long-haul systems consisting of optical amplifiers. The results indicate that the SSB technique with an optimum carrier suppression ratio reduces considerably the DML-induced nonlinear effect, and leads to decreased susceptibility of the aforementioned transmission performance to variations in DML operating condition and optical input power.
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