Single wavelength twin-SSB direct detection system based on Kramers-Kronig receiver and time-interleaved OFDM frame

In this paper, we propose a spectrally efficient and cost-effective twin-SSB OFDM system based on Kramers-Kronig optical phase reconstruction and time-interleaved frame (TIF). C-band transmission over 80 km SSMF with a net bit rate of 88.5 Gb/s using 40 GSa/s DACs is experimentally demonstrated with a BER threshold of 3.8e−3. Two optical filters are employed to separate the two sidebands at the receiver. The imperfection of filter transfer function introduces crosstalk between them, which can be mitigated by the TIF. The impact of optical filter parameters, including roll-off, bandwidth and center frequency shift, are studied and analyzed in detail by simulation. We show that the roll-off determines the required size of TIF, and the optical fiber bandwidth leads to tradeoff between carrier-to-signal power ratio and spectral efficiency. Finally, the optimization and tolerance range of the filter center frequency shift are numerically evaluated.