Transmission of 4-ASK Optical Fast OFDM With Chromatic Dispersion Compensation

We experimentally demonstrate transmission of 20-Gb/s four-amplitude-shifted-keying optical fast orthogonal frequency-division-multiplexing (F-OFDM) over various fiber lengths up to 840 km, and show that symmetric extension, instead of cyclic extension, based guard interval (GI) is required to enable chromatic dispersion (CD) compensation using one-tap equalizers after channel demultiplexing. We characterize the CD tolerance under different GI lengths and investigate the impact of fiber nonlinearity on the system performance.