Impact of in-band crosstalk due to mixed modulation formats with multiple line rates on direct-detection OFDM optical networks performance

The impact of in-band crosstalk on direct-detection (DD) orthogonal frequency division multiplexing (OFDM) optical networks performance is assessed in a mixed modulation formats with multiple data rates scenario. It is shown that differential phase-modulated signals lead to the highest crosstalk penalty, among the DD modulation formats typically used in optical networks, with a lower crosstalk tolerance of 2.5 dB in comparison with OFDM and on-off keying interfering signals. We also show that single-sideband OFDM signals exhibit a 3 dB lower inband crosstalk tolerance than double-sideband OFDM signals.