Programmable Microwave and Optical Pulse Generation Based on Coupled Optoelectronic Oscillator

We propose and experimentally demonstrate a method for generating programmable microwave and optical pulses using a coupled optoelectronic oscillator (COEO). An external low-frequency electrical signal is injected into both the optical fiber loop and optoelectronic loop of the COEO through a shared intensity modulator. When the period of the external signal matches the round-trip time of the optical fiber loop, it modulates the gain in both loops. Once the gain exceeds unity, microwave and optical pulses are generated in the respective loops. The durations and positions of these pulses within each period directly correspond to those of the external signal. Therefore, by manipulating the external signal, the durations and positions of the microwave and optical pulses can be flexibly controlled. In a proof-of-concept experiment, the proposed scheme initially generates a 9.985-GHz sinusoidal microwave signal along with an 11.47-ps optical pulse. The repetition rate of the optical pulses matches the frequency of the microwave signal. Subsequently, by controlling the external signals, microwave and optical pulse signals with duty cycles of 30%, 50%, and 70% are generated within a single period. Additionally, when external signals with double-pulse waveforms and programmable durations and positions are applied, the corresponding microwave and optical pulses are generated by the proposed scheme. The experimental results confirm that by programming the external signals, fully programmable microwave and optical pulses can be successfully generated.