Effect of laser and RF oscillator phase noises

The effect of phase noises from a laser and an oscillator on radio over fiber (RoF) systems is analyzed and discussed with a power spectral density (PSD) function. It is shown that the carrier to noise ratio (CNR) penalty is deeply related to the bandwidth of a electrical filter at a receiver and the phase noise from a radio frequency (RF) signal oscillator rather than that from a laser with a small differential delay and a direct detection scheme. The CNR penalties due to the laser linewidths of 10 MHz and 624 MHz are 0.045 dB and 2.78 dB, while the increase of the RF oscillator linewidth from 1 Hz to 10 Hz results in about 10 dB penalty at 50 GHz, 24 km transmission in a standard single mode fiber (SSMF) with a fiber chromatic dispersion of 17 ps/km nm.