Optical high repetition rate stabilization based an all-polarization-maintaining figure-of-nine Er-fiber laser

Optical frequency comb (OFC) based on mode-locked fiber lasers has abstracted extensive interest in the field of laser ranging and precision spectroscopy with its extremely high time–frequency accuracy. Therefore, the repetition rate stabilization plays a notably key role in OFC. Mechanical motion is generally used to change the geometric length of the laser cavity to stabilize the repetition rate. However, this method has some disadvantages such as high feedback voltage and mechanical disturbance caused by the characteristics of the piezoelectric ceramic transducer (PZT). To overcome these problems, the refractive index of the gain fiber can be regulated via controlling the pump power, thereby optically stabilizing the repetition rate. In this study, we reported the optical repetition rate stabilization via regulating the nonlinear refractive index of Er-fiber in an all-polarization-maintaining (PM) figure-of-nine laser cavity. The repetition rate reached 80.1 MHz and was stabilized for more than 1 h. The standard deviation (SD) was 178 μHz within 1-s gate time. As far as we know, in terms of optical repetition rate stabilization, the mode-locked Er-fiber laser achieved the highest repetition rate.