Absolute frequency measurement of rubidium 5S–7S two-photon transitions

Abstract

We report the absolute frequency measurements of rubidium 5S-7S two-photon transitions with a cw laser digitally locked to an atomic transition and referenced to an optical frequency comb. The narrow, two-photon transition, 5S-7S (760 nm), insensitive to first-order in a magnetic field, is a promising candidate for frequency reference. The performed tests yielded more accurate transition frequencies than previously reported.

Absolute frequency determination of molecular transition in the Doppler regime at kHz level of accuracy

“…The clock laser shifted by an AOM is digitally locked [27] to the 1 S 0 − 3 P 0 clock transition in ultracold 88 Sr atoms confined in a 1D optical lattice [12,13]. Long term frequency instability is below 10 −15 after 3 hours of averaging.…”

Strontium optical lattice clocks for practical realization of the metre and secondary representation of the second

“…Quadratic Zeeman -132(37) -126(19) The absolute frequency of the clock transition in our experimental set-up can be measured by the use of the Er:fiber optical frequency comb. At this stage of the experiment the optical frequency comb is locked to the GPS-disciplined standard which limits its accuracy on the level of 10 −12 [50]. Within this precision the measured absolute frequency of the clock transition in Sr1 is equal to 429 228 066 418 300(580) Hz.…”

Fibre-optic delivery of time and frequency to VLBI station

“…The clock laser frequency stabilization is performed by a frequency shifter that also removes slow linear frequency drift of the ultra-stable cavity. The frequency corrections are derived from the excitation probability on both sides of the atomic line (Morzyński et al 2013). The sample of atoms in the optical lattice is produced and interrogated every 1.3 s, therefore the servo loop cycle in our set-up is equal to 2.6 s. The instability in terms of the Allan deviation of the locked clock laser starts to decrease after few seconds averaging with a slope close to τ −1/2 , where τ is the averaging period.…”