A Threshold-Independent Approach to Stochastic Fluctuations in Optoelectronic Oscillators

Optoelectronic oscillators are time-delayed photonic systems able to generate pure microwave signals. The nonlinear dynamics of the systems can be well understood using an Ikeda-like equation governing the behavior of the output microwave envelope. This deterministic envelope equation can be converted into a stochastic phase dynamic equation using the Langevin approach, which accounts for both additive and multiplicative noise. Here, we can quantify the magnitude of the two noise contributions in the sub-threshold regime, and show that these measurements are predictive of the phase noise performance of the oscillator above threshold. Our theoretical analysis is found to be in excellent agreement with experimental measurements, which demonstrate a phase noise performance better than −130 dBc/Hz at 10 kHz offset from the carrier in the S-band.