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Frequency stability and comparison measurements have been undertaken between a pair of optical frequency standards based on the 2S½ - 2D5/2 transition in independent trapped 88Sr+ ions confined in two end-cap traps. A frequency stability of 2.5 × 10−16 at 4000 s has been measured, improving as τ−½. A null frequency offset at the 3 × 10−16 level has been measured. A measurement of the ratio of the...
We report on precision laser spectroscopy of the 2S1/2(F = 0) 2D3/2 (F = 2, mF = 0) clock transition in a single ion of 171Yb+. The absolute value of the transition frequency, determined using an optical frequency comb referenced to a hydrogen maser, is 688358979309310 ?? 9 Hz. This corresponds to a fractional frequency uncertainty of 1.3 ?? 10-14.
We report on precision laser spectroscopy of the 2S1/2(F = 0) - 2D3/2(F = 2, mF = 0) clock transition in a single ion of 171Yb+. The absolute value of the transition frequency, determined using an optical frequency comb referenced to a hydrogen maser, is 688 358 979 309 310 plusmn 9 Hz. This corresponds to a fractional uncertainty of 1.3 times 10-14.
To extend the range of utility of femtosecond comb technology at NPL, two comb systems are being built: a transportable system, to enable measurements to be made at locations other than our own laboratory; and a Cr:forsterite laser-based comb, to extend the spectral range to cover the telecommunications bands
A second femtosecond optical frequency comb has been implemented at NPL. This higher repetition rate system offers several advantages over our existing comb, and enables the accuracy of the frequency measurement process to be tested. Results of absolute frequency measurements carried out using the two different systems are compared
A pair of 1.5 mum diode laser frequency standards stabilized to 13C2H2 have been developed at NPL. Their stability and long-term reproducibility have been characterized, and the absolute frequencies of several acetylene lines measured using a combination of frequency chain, femtosecond comb and passive optical frequency comb technologies
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