Laser-pumped paraffin-coated cell rubidium frequency standard

Abstract

We have realized and studied a rubidium atomic frequency standard based on a paraffin-coated cell, exhibiting a short-term frequency stability <3 Â 10 À12 s À1/2 between s ¼ 1 and 100 s. Characterization of the wall-coating is performed by measuring the T 1 and T 2 relaxation times. Perturbations of the medium-to long-term clock stability, due to variations in the laser-intensity, laser frequency, the microwave power shift, and the shifts due to temperature variations are measured and analyzed. A method for reducing the intensity light-shift by detuning the laser frequency and the resulting improvement in clock stability is demonstrated. This work is of relevance for further improvements on Rb cell standards using anti-relaxation wall-coating technology.

Double-resonance in alkali vapor cells for high performance and miniature atomic clocks

“…Measured temperature coefficient of 1.5 x 10 -10 K -1 (comparable to the values found in literature [29,30]) and intensity light shift coefficients below 1.6x10 -12 /% are promising for competitive chip-scale and miniaturized clocks. The limitations for a high-performance clock using wall-coated cells were studied in [30].…”

Compact and frequency stabilized laser heads for Rubidium atomic clocks

“…In this way, the laser's frequency fluctuations are converted into amplitude fluctuations and the power spectral density of the frequency noise can be measured. As shown in Figure 2, values of 1x10 7 Hz 2 /Hz at 300 Hz have been obtained.…”

Non-negligible collisions of alkali atoms with background gas in buffer-gas-free cells coated with paraffin

“…Buffer-gas-free anti-relaxation-coated cells have a number of advantages over buffer-gas cells: the broadening of magnetic resonance lines due to field inhomogeneity can be reduced because alkali atoms sample the entire volume of the cell, and also it is possible to polarize and detect alkali atoms more effectively because there is no pressure broadening of the optical resonance line. Buffer-gas-free anti-relaxation-coated cells have therefore been used in many applications, including atomic clocks [3,4], ultra-sensitive magnetometry [5][6][7], quantum memory [8], and studies of light propagation [9]. In these experiments, the background gas pressure is thought to be low enough to ignore collisions between alkali atoms and the background gas.…”

“…• C. This shift may be problematic in atomic clock applications, considering the frequency shift induced by inner surfaces of a coated cell is on the order of a hundred Hz [3,4]. However, background gas pressures in buffer-gasfree cells have not been reported except for a very high pressure (≤ 600 Pa) background gas in a microfabricated cell with an octadecyltrichlorosilane coating [15].…”