Study of dual-loop optoelectronic oscillators

Dual-loop optoelectronic oscillators are used to obtain high-frequency harmonic signal with a very low phase noise while maintaining very low spurs. However, the fundamental limits of these devices are not known. Therefore, it is essential to develop theoretical models to improve the performance of dual-loop optoelectronic oscillators (OEOs) and in particular the performance of the dual-injection-locked optoelectronic oscillator (DIL-OEO). In this work we use a multi-time scale approach to model dual-loop OEOs. The model enables calculating the phase noise and the spurs level for an arbitrary coupling strength between the two locked OEOs. A good quantitative agreement between theory and experiments is obtained for the DIL-OEO.