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Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

A Rubidium Frequency-standard Based on a MEMS Vapour Cell

Steven Johnson, Allan McWillian, Eilidh MacLennan, Erling Riis, J. P. McGilligan, Paul F. Griffin

Published Jun 23, 2025• 0 citations
Publisher

Abstract

An optical atomic frequency-reference based on a vapour of atoms is a strong candidate for a creating a portable atomic clock with sufficient stability to be a reliable independent timing system for major infrastructure in the event of GNSS denial. We present the development of optical atomic frequency-standards within the University of Strathclyde, where MEMS vapour cells and lasers have been developed for a miniaturised rubidium frequency-reference. Existing chip-scale systems have been demonstrated by others using a microwave transition, however an optical clock offers a significantly higher frequency to enable a lower instability.

DOI
10.1109/cleo/europe-eqec65582.2025.11110643

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An optical atomic frequency-reference based on a vapour of atoms is a strong candidate for a creating a portable atomic clock with sufficient stability to be a reliable independent timing system for major infrastructure in the event of GNSS denial. We present the development of optical atomic frequency-standards within the University of Strathclyde, where MEMS vapour cells and lasers have been developed for a miniaturised rubidium frequency-reference. Existing chip-scale systems have been demonstrated by others using a microwave transition, however an optical clock offers a significantly higher frequency to enable a lower instability.
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In this talk, I will outline two stands of our ongoing atomic clock research at the University of Strathclyde, aimed at achieving short-term stabilities surpassing 1e-12 in portable systems. Firstly, I present a cold-atom microwave clock that integrates a grating-MOT within an additively manufactured microwave cavity, enabling a compact and potentially highly stable portable system. The work examines noise minimisation techniques through direct comparison with a cold-atom coherent population trapping (CPT) clock. I will also discuss progress on two-photon rubidium clocks based on MEMS vapour cells with integrated optics. The results highlight their prospects for resilient PNT applications and scalable deployment.
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Precision navigation and timing is an important focus in the Air Force Research Laboratory's experimental efforts. The development and testing of an optical frequency standard is suitable for an array of both terrestrial and space based applications. An optical atomic clock based upon a two-photon transition at 778 nm in rubidium, is an ideal candidate to meet the requirements of Global Satellite Navigation System (GNSS), while being a viable option for other applications. Here we demonstrate that a simple architecture, using off-the-shelf components and an external cavity diode laser system that is confined to less than 3 ft2 of breadboard, exhibits a frequency instability of 7 x 10-13/??, for times less than 100 seconds.
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