Optical frequency metrology with optical lattice clocks and optical frequency combs

Laser frequency stabilization and atom manipulation are important techniques for optical frequency metrology. We report on the development of an ytterbium (¹⁷¹Yb) and a strontium (⁸⁷Sr) optical lattice clock at the National Metrology Institute of Japan (NMIJ). The result of absolute frequency measurement of the ¹⁷¹Yb lattice clock is shown. We also report on narrow-linewidth fiber-based frequency combs that are used not only to measure the absolute frequency of the optical lattice clocks but also to servo control the frequency of the lasers for cooling and trapping Yb and Sr atoms.