40 Gb/s CAP32 short reach transmission over 80 km single mode fiber

We present a method to mitigate the chromatic dispersion (CD)-induced power fading effect (PFE) in high-speed and short-reach carrier-less amplitude and phase (CAP) systems using the degenerate four-wave mixing (DFWM) effect and a decision feedback equalizer (DFE). Theoretical and numerical investigations reveal that DFWM components produced by the interaction between the main carrier and the signal sideband help to mitigate PFE in direct detection systems. By optimizing the launch power, a maximum reach of 60 km in single mode fiber (SMF-e + ) at 1530nm is experimentally demonstrated for a 40 Gbit/s CAP32 system. In addition, we study the performance of a decision feedback equalizer (DFE) and a traditional linear equalizer (LE) in a channel with non-flat in-band frequency response. The superior PFE tolerance of DFE is experimentally validated, and thereby, the maximum reach is extended to 80 km. To the best of our knowledge, this is the twice the longest transmission distance reported so far for a single-carrier 40 Gbit/s CAP system around 1550 nm.