Microfabricated rubidium vapour cell with a thick glass core for small-scale atomic clock applications

Abstract

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.

A miniature frequency-stabilized VCSEL system emitting at 795nm based on LTCC modules

“…The diced preforms obtained are cleaned and prepared to be placed into a dedicated machine allowing dispensing alkali metal inside the cell cavity and closing it by bonding anodically a glass lid on top [12]. Before sealing the cell, a controlled pressure of gas mixture can be inserted into the machine and inside the cell cavity.…”

Miniaturized microwave cavity for rubidium atomic frequency standards

“…A sealed miniature cell of the type described in [10], containing Rb atomic vapor, is positioned inside the resonator, as shown in Fig. 5.…”

“…The μ-LGR was used for observing the DR signal of the 87 Rb clock transition. Laser light resonant with the Rb D2-line (780 nm) is sent through the μ-LGR containing a 4 mm-thick microfabricated Rb vapor cell [4], [10] (both held at 82°C). The light intensity transmitted through the cell is detected on the photodiode as a function of the microwave frequency injected into the μ-LGR, see Fig.…”

“…Solutions such as the magnetron-type MWR [7], miniature MWR using lumped LC elements [8], or slotted-tube MWR [9] were developed for Rb cells down to ≈1 cm size, but only few microwave structures for mm-scale cells are reported, based on strip-lines or micro coupling loops [6]. In this paper we present a miniature MWR, for use with 36 mm 3 micro-fabricated Rb cells [10]. The MWR is composed of a multi-layer stack of planar loop-gap resonator structures [11] printed onto substrates, and coupled to a coaxial fed strip-line.…”

Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

“…1(a)) is a microfabricated Rb cell (cylindrical inner volume: 5 mm height and 2.5 mm radius) with natural Rb isotopic mixture and 100 millibars of N 2 as buffer gas. 28 A high buffer gas pressure was chosen to reduce the number of depolarizing Rb atomic collisions with the cell walls and hence increase pumping efficiency. 13 Two 10 Â 3 Â 1 mm 3 Pyrex substrates with a 20 nm thick ITO thin film were glued to opposing cell sidewalls and used to heat the resonance cell by connecting them to an AC power supply (1.1 kHz frequency used).…”