The 199Hg+ single ion optical clock:: recent progress

We report on work directed toward the systematic evaluation of an optical frequency standard based on the S-2(1/2)-D-2(5/2) transition of a single, laser-cooled, trapped Hg-199(+) ion, whose resonance frequency is 1.06 x 10(15) Hz. For the purpose of the evaluation, two Hg-199(+) standards have been constructed. In the cooling-laser system built for the second standard, an injection-locking scheme has been applied to a cw Ti:sapphire laser. We also report optical frequency measurements of the clock transition pet-formed over the past 21 months with the first standard. During this term, the variation of the clock transition frequency is found to be less than one part in 10(14).