Analysis of Injection Locking and Pulling in Single-Loop Optoelectronic Oscillator

Injection-locking characteristics of a single-loop optoelectronic oscillator (OEO) under an independent sinusoidal RF signal injection are investigated. The mathematical model of the unlocked-driven system is developed to represent phase perturbation of the generated output RF signal caused by the RF injection signal. The closed-form expressions of the output RF spectra distorted due to RF signal injection are derived to formulate the behavior of the injection-pulled OEO. Using the phase dynamics equation, a phase noise model is developed to quantify the influence of RF injection signal on the phase noise performance of the oscillator. It is shown that our analytical model is capable of predicting the injection locking and estimating the injection pulling behavior of the single-loop OEO under RF signal injection. The theoretical results are validated by the experimental results.