Iodine Optical Frequency Standard with Hybrid Frequency Stabilization System on a High-Finesse Cavity

Wedemonstrate a method to combine a molecular iodine absolute frequency reference with a high-finesse optical cavity to take advantage of the frequency stability properties of both systems at different timescales. The result is a frequency-stabilized single Nd:YAG laser with the long-term and short-term stability levels of the iodine frequency reference and optical cavity, respectively. Experimental results show cavity-limited instability $5 \cdot 10^{-15}$ at time scales of 1 s and iodine instability below $10^{-15}$ for observation times of $10^{4} \mathrm{~s}$.