Precision stabilization of femtosecond lasers to high-finesse optical cavities

We report on direct stabilization of a femtosecond laser by a high-finesse passive optical cavity. Detailed comparison of two distinct stabilization schemes leads to new understanding of the optimum conditions for cavity stabilization and limitations on the ability to transfer the frequency stability of the cavity to the microwave domain. The stability of the frequency comb is explored in both the optical and the radio frequency domain. With an independent, stable cw laser, we verify that the linewidth and stability of the optical comb components, respectively, reach below $300\text{Hz}$ and $5\times {10}^{-14}$ at 1 s averaging time, both limited by the reference cw laser.