“…In microwave photonic radar system, high-quality multi-wavelength light sources are required, and the high-quality optical frequency comb (OFC) with high flatness, a large number of comb lines and the tunable frequency interval are considered as a research hotspot, and can be applied in WDM system [1], photonic filtering [2] and optical millimeter wave generating [3], etc. In the past decade, various schemes have been proposed for generating OFC, for instance the optical nonlinear effect method [4], the mode-locked laser method [5], the photoelectric oscillator method [6], and the external modulator method [7][8][9][10].…”