Amplifier enhanced gain-through-filtering instability in a hybrid Kerr cavity

We investigate analytically, numerically and experimentally the gain-through-filtering modulation instability in a hybrid driven Kerr cavity in the normal dispersion regime including an erbium-doped fiber amplifier. We show that, thanks to the increased cavity finesse enabled by the intracavity optical gain, the injection power threshold for the modulation instability can be substantially reduced, and the energy transfer to spectral sidebands enhanced. Our findings demonstrate how to improve efficiency and bandwidth in optical frequency comb generation based on the gain-through-filtering modulation instability.