Potentials and challenges for optoelectronic oscillator

We review our experimental and simulation-modeling studies on optoelectronic oscillators (OEOs). The OEO can have an intrinsic quality factor, Q that is orders of magnitude higher than that of the best electronic oscillators (i.e. Poseidon). However, our experimental results show that the OEO's current phase noise level is still worse than that of the Poseidon. This is caused by many noise sources in the OEO which reduce the "loaded-Q" in the loop system. In order to mitigate these noise sources, we have systematically studied such phenomena as the laser RIN, Brillouin and Rayleigh scattering in the fiber, vibration, etc. These noise sources are convoluted in both optical and electrical domains by many different physical effects; hence, it is very difficult to experimentally separate them, and only the dominant phase noise is observed in each offset-frequency. Therefore, we developed a computational model to simulate our experimental injection-locked dual-OEO system. By validating the model with our experimental results from both individual components and OEO loops, we can start to trace the individual phase noise sources. The goal is to use the validated model to guide our experiments to identify the dominant phase noise in each spectral region, and mitigate these noise sources so that the OEO can reach its full potential.