A photonic-based reconfigurable microwave frequency divider using two cascaded dual-parallel Mach-Zehnder modulators (DP-MZMs) is proposed. The first DP-MZM is driven by the input microwave signal, whereas the second DP-MZM is incorporated in an optoelectronic oscillator (OEO) loop and driven by the feedback signal. By properly setting the working conditions of the two DP-MZMs, the frequency of the input microwave signal is divided and the frequency-divided signal will oscillate in the OEO loop, with a tunable frequency-division factor determined by the bias conditions of the DP-MZMs. An experiment is performed. The reconfigurable microwave frequency divider is demonstrated with a frequency-division factor of 1.5, 2.5, 2, or 3, and the phase noise of the frequency-divided signals is also evaluated, which has an improvement of 3.22, 7.60, 5.80, or 9.49 dB at 10-kHz frequency offset, respectively, compared with that of the input microwave signals.
A photonics-enabled analog wavelet-like transform system, characterized by multiscale time-frequency analysis (TFA), is proposed based on a typical stimulated Brillouin scattering (SBS) pump–probe setup using an optical nonlinear frequency-sweep signal. The periodic SBS-based frequency-to-time mapping (FTTM) is implemented by using a periodic nonlinear frequency-sweep optical signal with a time-varying chirp rate. The frequency-domain information of the signal under test (SUT) in different periods is mapped to the time domain via the FTTM in the form of low-speed electrical pulses, which is then spliced to analyze the time-frequency relationship of the SUT in real-time. The time-varying chirp rate in each sweep period makes the signals with different frequencies have different frequency resolutions in the FTTM process, which is very similar to the characteristics of the wavelet transform, so we call it a wavelet-like transform. An experiment is carried out. Multiscale TFA of a variety of RF signals is carried out in a 4-GHz bandwidth limited only by the equipment.
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