Period-Doubling Optoelectronic Parametric Oscillator for Reconfigurable Microwave Waveform Generation

In this paper, a novel period-doubling optoelectronic parametric oscillator (OEPO) based on the in-loop nonlinear dynamics is proposed. The proposed system is built upon the conventional single-loop optoelectronic oscillator (OEO) architecture, incorporating an additional broadband filter in parallel with the narrowband filter. By injecting an external microwave signal into the OEO, two mutually coupled oscillation modes, whose sum frequency equals the injected microwave signal, can simultaneously survive and oscillate. The two oscillating frequencies reach self-consistency every two round trips through frequency conversion and energy coupling in the Mach-Zehnder modulator (MZM) and the photodetector. When the loop gain slightly exceeds the oscillation threshold, the OEPO can oscillate at two pure frequencies with proper phase matching. As the loop gain gradually increases to a sufficiently high level, a Hopf bifurcation will occur in the amplitudes of the two surviving modes due to nonlinear effects, leading to frequency-hopping behavior in the output microwave waveform. In a proof-of-concept experiment, the OEPO successfully generates a phase-coherent dual-frequency microwave signal or a frequency-hopping microwave signal with frequencies ranging from 6.5 to 12 GHz. This work demonstrates a novel oscillation mechanism in OEPO, providing reconfigurable microwave waveform generation capabilities that could be applied in emerging wireless communications and advanced electronic warfare systems.