Phase noise measurement of an optoelectronic oscillator based on the photonic-delay line cross-correlation method

Phase noise measurement of a dual-loop optoelectronic oscillator (OEO) based on a dual- photonic-delay line cross-correlation method is proposed and experimentally demonstrated. The dual-loop OEO and the phase noise measurement system are combined by sharing the transmitter of the optical link, which makes the structure of the system simpler. In part of the dual-loop OEO, the 10 km long fiber is shared by the two loops of the OEO utilizing a wavelength division multiplexing technique. Higher quality factors are obtained simultaneously by the two loops. In part of the phase noise measurement system, a lower phase noise floor is realized through a cross-correlation method. In the experiments, a signal with oscillation frequency of 10.664 GHz and a side-mode suppression ratio of 82.4 dB is generated. Its phase noise is evaluated by the proposed system and PN9000C. The measured results of the two systems are in perfect agreement. The phase noise of the signal is measured as -122  dBc/Hz at a 10 kHz frequency offset, and the phase noise floor of the 10 μs delay phase noise measurement system is -148  dBc/Hz at a 10 kHz offset at 10.6 GHz, when the number of averaged results is 100.