  For coherent and direct-detection Orthogonal Frequency Division Multiplexed
(OFDM) systems employing radio frequency (RF) pilot tone phase noise
cancellation the influence of laser phase noise is evaluated. Novel analytical
results for the common phase error and for the (modulation dependent) inter
carrier interference are evaluated based upon Gaussian statistics for the laser
phase noise. In the evaluation it is accounted for that the laser phase noise
is filtered in the correlation signal detection. Numerical results are
presented for OFDM systems with 4 and 16 PSK modulation, 200 OFDM bins and baud
rate of 1 GS/s. It is found that about 225 km transmission is feasible for the
coherent 4PSK-OFDM system over normal (G.652) fiber.
