Flat microwave frequency comb generation based on stimulated Brillouin scattering

A photonic-based approach for generating flat microwave frequency comb is proposed and experimentally demonstrated. By selectively amplifying a specific line of an optical frequency comb with a flat optical spectral profile— enabled by the narrowband gain of stimulated Brillouin scattering—the flat optical spectrum is mapped to the electrical spectrum, resulting in a flat microwave frequency comb. In the experiment, an optical frequency comb is mapped to the electrical spectrum, producing a 9-line microwave frequency comb with a flatness of 1.04 dB and an inverted Sinc-shaped waveform in the time domain.