Improving the performance of the injection-locked optoelectronic oscillator by using an extra feedback loop

We describe and demonstrate a practical method for improving the performance of an injection-locked optoelectronic oscillator (IL OEO). An improved IL theory model, which helps to set the optimal locking range and reduce the phase noise of the OEO, is proposed. The IL OEO with an extra feedback loop exhibits good long-term operating stability and can produce a 10 GHz output signal with 80 dB side-mode suppression ratio and better than ± 0.0005 ppm frequency drift within 12 h. The presented results can be used to guide the design of high-quality OEOs.