Generation of multi-band reconfigurable microwave waveforms based on dual-chirped fiber combs

A scheme for the photonic generation of multi-band reconfigurable microwave waveforms (MRMWs) is proposed and demonstrated based on dual-correlated chirped fiber combs. In the proposed system, the output of master laser is split into two paths, and then respectively coupled with another a single-frequency fiber laser and amplified for the generation of dual combs, which also acts as the reference frequency. During various formats wavelength sweeping operation, one of the single-frequency lasers can flexibly manipulate the repetition-rate difference of the dual-comb. Meanwhile, the chirp from a pump laser is transferred to all spectral comb teeth through the intra-cavity cascaded four-wave mixing process at once. After optical filtering, by beating the paired comb lines of the same order at a high-speed photodetector (PD), the bandwidth, central frequency and repetition rate of the chirped microwave waveforms are obtained. This system has a compact structure without electro-optical modulators and takes into account mutual coherence.