Frequency stabilization of mode-locked Erbium fiber lasers using pump power control

Mode-locked erbium fiber lasers can serve as frequency comb generators in the 1.5 m telecommunication band or as frequency dividers generating low noise pulse trains at microwave repetition rates from a visible or near infrared frequency standard. Such applications require suitable stabilization methods both for the lasers carrier frequency and the pulse repetition frequency. While control of the optical resonator length with the help of a piezo actuator is an obvious method, we investigate in this paper frequency stabilization of the fiber laser via pump power control. Using this method, we stabilize the pulse repetition rate of the Er:fiber-laser with respect to a hydrogen-maser with residual averaged timing errors of a few femtoseconds (for averaging times between one and one hundred seconds), an order of magnitude below the timing noise of the maser itself. PACS 42.55Wd; 42.62.Eh