Photonic frequency division of broadband microwave signal based on a Fourier domain mode-locked optoelectronic oscillator

A novel photonic approach to realizing frequency division of broadband microwave signal based on a Fourier domain mode-locked optoelectronic oscillator (FDML-OEO) is proposed and experimentally demonstrated. Thanks to the mechanism of Fourier domain mode-locking, a conventional OEO system with the Mach-Zehnder modulator (MZM) biased at null point can be used to achieve frequency division, which is implemented by precisely matching the delay of the OEO loop with the period of the injected signal. The conditions to achieve frequency division of broadband microwave signal are theoretically analyzed, and experimental demonstration is performed to verify the effectiveness of the proposed system. In the experiment, a linear frequency modulation (LFM) signal is injected for verification. By tuning the delay of the OEO loop, the frequency, the bandwidth and the chirp rate of the injected LFM signal are all half-divided. Frequency divisions of LFM signals with different central frequencies and bandwidths are demonstrated. The phase noise of the divided signal is improved by 4.43 dB as compared to that of the injected signal. The results demonstrate, for the first time, a frequency divider for broadband microwave signal division based on an OEO.