February 2023
Spotlight Summary by James P. McGilligan
Microfabricated strontium atomic vapor cells
The transition from alkali atoms to alkaline earth atoms in microfabricated vapor cells offers alluring opportunities for optical metrology at the chip-scale. However, to compensate for the relatively low vapor density of alkaline earth atoms, the operational temperature of the cell ranges beyond 300ºC, providing a challenge in sustaining cell longevity. Indeed, at these elevated temperatures the alkaline earth metal reacts with the glass windows of the cell to degrade their transparency. Coating the glass with a protective material can be considered to overcome this issue. However, this raises the technical challenge of harnessing vapor deposition techniques that remain compatible with a microfabricated cell.
In this work, J. M. Pate et. al. demonstrate the micro-fabrication of a strontium atomic vapor cell, with a silicon body hermetically sealed to glass wafers coated in a layer of Al2O3 to protect the glass and extend cell longevity. The transmission of off-resonant light is used to measure any temporal change in glass transparency for different glasses with and without coating, to provide insight to any improvement factor. While the uncoated glass transmission is rapidly degraded by the presence of the strontium vapor, the coated glass shows no significant reduction in transmissivity beyond 380 hours of operation at 300ºC. Importantly, from spectroscopy carried out on the transition, the authors show a low level of background gas contamination from a strontium metal source loaded into the chamber under an argon environment. These early demonstrations provide critical insight to the available routines that can enable the transfer of this technology to more exotic atomic species, while preserving cell longevity and providing a suitably clean vapor density.
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In this work, J. M. Pate et. al. demonstrate the micro-fabrication of a strontium atomic vapor cell, with a silicon body hermetically sealed to glass wafers coated in a layer of Al2O3 to protect the glass and extend cell longevity. The transmission of off-resonant light is used to measure any temporal change in glass transparency for different glasses with and without coating, to provide insight to any improvement factor. While the uncoated glass transmission is rapidly degraded by the presence of the strontium vapor, the coated glass shows no significant reduction in transmissivity beyond 380 hours of operation at 300ºC. Importantly, from spectroscopy carried out on the transition, the authors show a low level of background gas contamination from a strontium metal source loaded into the chamber under an argon environment. These early demonstrations provide critical insight to the available routines that can enable the transfer of this technology to more exotic atomic species, while preserving cell longevity and providing a suitably clean vapor density.
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Article Information
Microfabricated strontium atomic vapor cells
Jacob M. Pate, John Kitching, and Matthew T. Hummon
Opt. Lett. 48(2) 383-386 (2023) View: Abstract | HTML | PDF