Narrow-linewidth and highly stable optical frequency comb realized with a simple electro-optic modulator system in a mode-locked Er:fiber laser

We demonstrate a mode-locked Er:fiber laser with a compact fiber-pigtailed optical bench containing a free-space electro-optic modulator for high-speed feedback control. The achieved servo bandwidth of the beat frequency between a given comb component and a reference laser is approximately 850 kHz. The realization of a narrow-linewidth and highly stable frequency comb is confirmed by measuring both in-loop and out-of-loop beat frequencies. We also demonstrate the frequency measurement of two iodine-stabilized Nd:YAG lasers through the narrow-linewidth comb without stability degradation. The developed optical frequency comb can work continuously for weeks without maintenance.