Generation of high-repetition-rate optical frequency comb based on FWM in a Brillouin ring cavity

As a single optical source, optical frequency comb (OFC) exhibits high coherence, low phase noise, and stable multi-wavelength output, enabling it to gradually replace multiple lasers traditionally used in wavelength division multiplexing (WDM) systems, thereby significantly improving spectral efficiency and effectively reducing energy consumption. In this work, we demonstrate a high-quality OFC generation scheme with tunable repetition frequency. The OFC is generated based on stimulated Brillouin scattering (SBS) and four-wave mixing (FWM) effects in highly nonlinear fiber (HNLF), and the repetition frequency of the OFC is tunable to 100 GHz, 200 GHz, or 300 GHz by controlling the frequency interval of the dual-wavelength, continuously pumped laser. When the repetition frequency is fixed at 100 GHz, increasing the current of the erbium-doped fiber amplifier (EDFA) extends the OFC spectral coverage to as wide as 39.7 nm, supporting up to 44 comb lines.