High-Speed Ultra-Short Electric Pulse Train Generation Based on Regenerative Rational Harmonic Excitation in a Broadband Optoelectronic Oscillator

Spiking pulses are localized structures under the balance of nonlinearity, filtering, loss and gain in broadband optoelectronic oscillators (OEOs), which are triggered by initial weak perturbations and can maintain stable oscillation due to the bistable effect. Here, a regenerative rational harmonic excitation scheme is proposed to achieve high-speed electric pulse generation in a broadband nonlinear OEO. Through injecting a periodic perturbation signal with a repetition frequency equal to a rational multiple of the free spectral range (FSR) into the OEO cavity, a spiking pulse train with a high pulse repetition frequency is excited. After turning off the external excitation source, a stable ultra-short spiking pulse train is regenerated. Both numerical simulations and experiments are carried out to study the dynamic process of the proposed scheme and to demonstrate its potential to generate high-speed ultra-short electric pulse trains. In the experiment, ultra-short pulse trains with repetition frequencies of 8 × FSR and 24 × FSR are generated based on (2 + 2/3)th-order and (3 + 3/7)th-order harmonic excitation, respectively, which shows excellent pulse-to-pulse consistency. This scheme paves a way to generate high-speed ultra-short pulse trains via using low-speed digital circuits.