All-Optical High-Precision Repetition Rate Locking of an Yb-Doped Fiber Laser

We demonstrated an all-optical stabilization of the repetition rate in an all-fiber picosecond fiber laser. An active Er-doped fiber was added in the Yb-doped fiber cavity as an optical length modulator via refractive index change with optical pumping at 976 nm to achieve repetition rate stabilization. The standard deviation of the residual fluctuation was 1.39 mHz in a 1 h measurement with a linewidth and phase noise of 1.6 mHz and 0.55 rad, respectively.