Experimental Demonstration of a 16.27 Gb/s 2-D Coherent Optical OFDM System With 3-D Signal Mapper and 2-D IFFT Modulator

We propose a coherent optical OFDM (CO-OFDM) system based on 3-dimensional (3-D) OFDM technique in this paper. By using the 3-D signal mapper and 2-D IFFT module, the minimum Euclidean distance (MED) in constellations is increased by 8.7%, and the peak-to-average power ratio of the generated OFDM signal is reduced by 4 dB. The experimental results show that the 3-D OFDM method can improve nonlinearity tolerance by 2 dB for 100-km standard single mode fiber in a 16.27-Gb/s 2-D coherent optical OFDM system without polarization modulation. Theoretical analysis and simulation results show that the OSNR penalty could be attributed to the increased MED, the extended decision boundaries and the coding gain. To further analyze the performance in long haul transmission system, the simulation setup of 1000-km SSMF CO-OFDM system is built up. The results verify that the proposed method could effectively enhance nonlinearity tolerance and transmission performance of the CO-OFDM system.