Frequency verniers of Ti:sapphire laser

By precisely controlling the comb laser repetition rate, we resolved a dark state of exceptionally narrow linewidth (5.6 Hz) in cesium gas buffered by neon atoms. We theoretically interpreted our experimental data and pointed out that this narrow resonance potentially can not only be used to enhance the frequency discrimination of microwave clock to sub-10-Hz level, but also to transport a well-stabilized clock signal optically via Ethernet, referring to the same atomic ensemble. Together with 822-nm and 884-nm cesium two-photon-stabilized diode lasers, we established a set of optical frequency verniers for a Ti:sapphire comb laser.