High-bandwidth large-dynamic frequency control of an optical comb by tuning polarization state

We report a new method to precisely control carrier-envelope frequency (fceo) of a nonlinear-polarization-rotation mode-locked Er:fiber optical frequency comb. The fceo is phase-locked onto an RF reference frequency by rotating polarization state with a special home-made intra-cavity electro-optic modulator (EOM). The EOM is inserted right after the PBS of a well-known ring mode-locked laser's loop and rotates polarization state with a coefficient of about 1.2 × 10−4 rad/v in ellipticity. The frequency control range of the EOM is two orders of magnitude larger than the traditional ones. Benefiting from fast response of the EOM, in-loop frequency stabilities of the fceo is below 2×10−17 at 1 second, and the corresponding timing jitter is about 0.16 rad.