Demonstration of Direct Detected Optical OFDM Signals via Block-Wise Phase Switching

In this paper, we propose and demonstrate phase switching for either main carrier or subcarriers of two consecutive signal blocks to achieve fading-free double-sideband direct-detection. The proposed approach has twice of the electrical spectral efficiency (SE) of offset OFDM, and the same electrical SE as single-side band OFDM. We perform numerical simulation and verify the system robustness against polarization mode dispersion and laser phase noise. Our experimental results show that 40-Gb/s direct-detection OOFDM can be successfully delivered over 80-km SSMF with single polarization and single detector.