On the Phase Noise Impact in Direct-Detection Optical OFDM Transmission

In this letter, we characterize the impact of laser phase noise (PN) in direct-detection optical orthogonal frequency-division multiplexing (OFDM) and emphasize its several differences from those in coherent optical OFDM. We also analyze the system performance in the presence of PN for various quadrature-amplitude-modulation formats and provide the bit-error-rate estimation method which can yield reliable results when the PN-induced optical signal-to-noise ratio penalty is lower than ~2 dB.