Improved SC-FDE With Noise Filtering for Directly Detected WDM-PON

We propose a modified single-carrier frequency domain equalization (SC-FDE) scheme implemented in directly detected wavelength-division-multiplexed passive optical networks (WDM-PONs). A time-clipping technique is used in FDE to perform noise filtering. In the simulation, where the channel is modeled with chromatic dispersion and direct detection, performance improvement is achieved by exploring the clipping position and retained gradient vector length. In the experiment, we investigate the time-clipping SC-FDE implemented in 10-Gb/s direct-detected WDM-PON using an uncooled free-running 1550-nm vertical cavity surface emitting laser. After 30-km transmission, it is observed that the time-clipping scheme can bring roughly 1-dB power penalty improvement over conventional equalization schemes.