Constant envelope OFDM transmission over metro-regional optical links

The transmission of constant envelope orthogonal frequency division multiplexing (CE-OFDM) signals is experimentally demonstrated in this paper to increase the reach of metro-regional optical links. A recirculating fiber loop was implemented for this aim. A reach extension of 100 km of standard single-mode fiber was achieved with the CE-OFDM-based system, considering 16 quadrature amplitude modulation (16-QAM) as subcarrier mapping and links without optical dispersion compensation. Link lengths as long as 700 km, with spectral efficiency of 1.89 b/s/Hz, were accomplished with performances below the forward error correction limit.