Development of a 1 Hz relative linewidth Er:fiber comb utilizing a semiconductor saturable absorber mirror

Abstract An Er:fiber comb based on a mode-locked Er:fiber laser was developed, employing a semiconductor saturable absorber mirror and an intra-cavity electro-optic modulator. The carrier-envelope offset frequency of the comb was phase-locked with a servo bandwidth of 60 kHz using a divide-by-10 frequency divider. Subsequently, the Er:fiber comb was phase-locked to an iodine-stabilized Nd:YAG laser with a servo bandwidth of 550 kHz, without the necessity of a frequency divider. Furthermore, the relative linewidth of the developed Er:fiber comb was evaluated by comparing it with another optical frequency comb, confirming that the relative linewidth was less than 1 Hz.