Low Phase Noise and Highly Stable Optoelectronic Oscillator by Using Frequency-Multiplying Phase Locked Loop

Photonic-based optoelectronic oscillator (OEO) is a good candidate to generate high spectral purity microwave signal. To improve its frequency accuracy and long-term stability, an analog phase locked loop (PLL) by using a double balanced mixer as phase detector is widely used. However, due to the limitations of the acquisition range and pull-in time of the analog mixer based PLL, it is hard to realize a highly stable OEO. In this paper, we use a frequency-multiplying PLL with a phase and frequency detector to stabilize the frequency of OEO. The utilization of digital phase and frequency detector can enlarge the acquisition range and reduce the pull-in time of the phase locked OEO. Experimentally, we attain a 9.2 GHz microwave signal with single-sideband (SSB) phase noise of -110 dBc/Hz at 10 kHz offset and Allan deviation of 10
^-10
at average time of 1000 s.