Ground state hyperfine structures of 43K and 44K measured by atomic beam magnetic resonance coupled with laser optical pumping

The ground state hyperfine structures of 43 K and 44K have been measured by an atomic beam magnetic resonance method in which the atoms are spin-polarized by laser optical pumping. The spectroscopic results are : Δv43( 2S1/2) = 192.648 4 (30) MHz and Δν44( 2S1/2) = - 946.718 (3) MHz. The sensitivity of our method is compared to the one achieved in classical ABMR apparatus

A New Optical Wavelength Ratio Measurement Apparatus: The Fringe Counting Sigmameter

International audienceA new, compact and achromatic Michelson-type interferometer with a variable path difference is presented. This "fringe-counting" sigmameter allows measurement of optical wavelength ratios between a laser of unknown wavelength and a reference laser of known wavelength. This apparatus, maintained in a vacuum, measures interference order variations in two stages: integer counting of around 400 000 and fractional counting (also called "excess fraction") with an uncertainty of 10. From these measurements, this "sigmameter" can determine laser wavelength from 0.36 m to 1.5 m with an accuracy of 1.10 using a reference stabilized He-Ne laser

Generation of 656 nm coherent red-light by frequency-doubled Nd:YLiF4/β-BaB2O4 laser for a compact silver atoms optical clock

International audienceWe describe an efficient continuous-wave diode-pumped Nd:YLiF4 laser oscillating on theσ-polarized 4F3/2−4I13/2 transition at λω = 1312 nm. With a simple linear cavity laser, we reached anintracavity power of 310 W at λ = 1312 nm for 16 W of absorbed pump power (λp ∼ 806 nm). A 0.25 Wof tunable radiation (λ2ω = 656−658 nm) was obtained by intracavity second-harmonic generation (SHG)with a 5×5×7 mm3 β-BaB2O4 crystal. Up to 10 mW of tunable single-frequency operation was observedusing a 200 μm thin fused silica intracavity solid etalon. The optimal waist for a maximum conversionefficiency has been calculated theoretically using Boyd and Kleiman model. For the 1312−656 nm SHG,we found a walk-off parameter B = 8.99 and an optimal waist of 25 μm. Comparing to the experimentalmeasurement of the optimal waist, we found a relative discrepancy of 2.84 × 10−2. This laser is dedicatedto the spectroscopic study of silver atoms trapped in a buffer-gas-free paraffin coated Pyrex cell that willbe used in a compact atomic optical clock

First determination of the Planck constant using the LNE watt balance

International audienceAfter separate developments of the different elements with continuous characterizations and improvements, the LNE watt balance has been assembled. This paper describes the system in detail and gives its first measurements of the Planck’s constant h. The value determined in air is h = 6.626 068 8(20) × 10-34 Js which differs in relative terms by -0.05  ×  10-7 from the h90 value and by -1.1  ×  10-7 from that of the 2010 CODATA adjustment of h. The relative standard uncertainty associated is 3.1  ×  10-7