Analog wavelet-like transform based on stimulated Brillouin scattering

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.