Analysis of the mode composition of an X-band overmoded O-type Cerenkov high-power microwave oscillator Phys. Plasmas 19, 103102 (2012) Gap independent coupling into parallel plate terahertz waveguides using cylindrical horn antennas J. Appl. Phys. 112, 073102 (2012) A band-pass filter approach within molecular dynamics for the prediction of intrinsic quality factors of nanoresonators J. Appl. Phys. 112, 074301 (2012) A research of W-band folded waveguide traveling wave tube with elliptical sheet electron beam Phys. Plasmas 19, 093117 (2012) Additional information on Rev. Sci. Instrum. The design, realization, and characterization of a compact magnetron-type microwave cavity operating with a TE 011 -like mode are presented. The resonator works at the rubidium hyperfine ground-state frequency (i.e., 6.835 GHz) by accommodating a glass cell of 25 mm diameter containing rubidium vapor. Its design analysis demonstrates the limitation of the loop-gap resonator lumped model when targeting such a large cell, thus numerical optimization was done to obtain the required performances. Microwave characterization of the realized prototype confirmed the expected working behavior. Double-resonance and Zeeman spectroscopy performed with this cavity indicated an excellent microwave magnetic field homogeneity: the performance validation of the cavity was done by achieving an excellent short-term clock stability as low as 2.4 × 10 −13 τ −1/2 . The achieved experimental results and the compact design make this resonator suitable for applications in portable atomic high-performance frequency standards for both terrestrial and space applications.
We present a new characterisation technique for atomic vapor cells, combining time-domain measurements with absorption imaging to obtain spatially resolved information on decay times, atomic diffusion and coherent dynamics. The technique is used to characterise a 5 mm diameter, 2 mm thick microfabricated Rb vapor cell, with N2 buffer gas, placed inside a microwave cavity. Time-domain Franzen and Ramsey measurements are used to produce high-resolution images of the population (T1) and coherence (T2) lifetimes in the cell, while Rabi measurements yield images of the σ−, π and σ+ components of the applied microwave magnetic field. For a cell temperature of 90• C, the T1 times across the cell centre are found to be a roughly uniform 265 µs, while the T2 times peak at around 350 µs. We observe a 'skin' of reduced T1 and T2 times around the edge of the cell due to the depolarisation of Rb after collisions with the silicon cell walls. Our observations suggest that these collisions are far from being 100% depolarising, consistent with earlier observations made with Na and glass walls. Images of the microwave magnetic field reveal regions of optimal field homogeneity, and thus coherence. Our technique is useful for vapor cell characterisation in atomic clocks, atomic sensors, and quantum information experiments.
This paper presents a new fabrication method to manufacture alkali reference cells having dimensions larger than standard micromachined cells and smaller than glass-blown ones, for use in compact atomic devices such as vapour-cell atomic clocks or magnetometers. The technology is based on anodic bonding of silicon and relatively thick glass wafers and fills a gap in cell sizes and technologies available up to now: on one side, microfabrication technologies with typical dimensions 2 mm and on the other side, classical glass-blowing technologies for typical dimensions of about 6-10 mm or larger. The fabrication process is described for cells containing atomic Rb and spectroscopic measurements (optical absorption spectrum and double resonance) are reported. The analysis of the bonding strength of our cells was performed and shows that the first anodic bonding steps exhibit higher bonding strengths than the later ones. The spectroscopic results show a good quality of the cells. From the double-resonance signals, we predict a clock stability of ≈3 × 10 −11 at 1 s of integration time, which compares well to the performance of compact commercial Rb atomic clocks.
Abstract-We present the development and complete spectral characterization of our compact and frequency-stabilized laser heads, to be used for rubidium atomic clocks and basic spectroscopy. The light source is a Distributed Feed-Back (DFB) laser diode emitting at 780 nm or 795 nm. The laser frequency is stabilized on a sub-Doppler absorption peak of the 87 Rb atom, obtained from an evacuated rubidium cell. These laser heads, including the electronics for the light signals detection, have an overall volume of 0.63 liters. We also present a variant of the laser head into which is integrated an Acousto-Optical Modulator (AOM) that precisely detunes the laser frequency in order to minimize the AC Stark shift in Rb atomic clocks.
We present a microfabricated alkali vapor cell equipped with an anti-relaxation wall coating. The anti-relaxation coating used is octadecyltrichlorosilane and the cell was sealed by thin-film indiumbonding at a low temperature of 140 C. The cell body is made of silicon and Pyrex and features a double-chamber design. Depolarizing properties due to liquid Rb droplets are avoided by confining the Rb droplets to one chamber only. Optical and microwave spectroscopy performed on this wallcoated cell are used to evaluate the cell's relaxation properties and a potential gas contamination. Double-resonance signals obtained from the cell show an intrinsic linewidth that is significantly lower than the linewidth that would be expected in case the cell had no wall coating but only contained a buffer-gas contamination on the level measured by optical spectroscopy. Combined with further experimental evidence this proves the presence of a working anti-relaxation wall coating in the cell. Such cells are of interest for applications in miniature atomic clocks, magnetometers, and other quantum sensors.Microfabricated alkali vapor cells are widely studied and employed for miniature devices such as atomic magnetometers, 1 atomic clocks, 2,3 or other quantum sensors. 4 The required low relaxation rates of the atomic ground-state polarization are generally achieved by adding buffer gases to the cells, which results in decreased collision rates of the alkali atoms with the cell walls, longer ground-state polarization lifetime, and therefore improved stability in the case of an atomic clock. Alternatively, the lifetime of the polarization can be increased by depositing anti-relaxation coatings on the cell walls. [5][6][7] Macroscopic ($few cm) alkali vapor cells equipped with anti-relaxation wall coatings have shown to be effective for the development of atomic clocks 5,8 and magnetometers.9,10 Such coatings are also of interest for miniature atomic clocks 8,11,12 and several studies aimed at finding an optimal coating that is compatible with microfabrication, 11,13 in particular, in view of the elevated process temperatures.
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