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arXiv · 2606.05987

Laser fractional frequency instability at $\mathbf{4\times 10^{-17}}$ with a room temperature optical reference cavity

Adam L. Parke·Eve Clulow·Wei Huang·Namneet Kaur·Reinhard Karembera·Jacques-Olivier Gaudron·Xi Zhang·Matias Risaro·Jacob Tunesi·Henry Bourne·Marco Schioppo
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Abstract

Ultrastable lasers play a key role in optical frequency metrology, setting measurement speed and ultimately impacting both stability and accuracy of optical frequency standards. Here we demonstrate laser fractional frequency instability at ${4}\times10^{-17}$ and laser frequency linewidth of $12\,$mHz full width at half maximum, employing a 68 cm long optical reference cavity operating at room temperature. To the best of our knowledge, both frequency instability and linewidth are the lowest ever reported for a room temperature system. This work highlights that state-of-the-art frequency stability and spectral purity are achievable at room temperature, making them accessible to a broader range of users.

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Adam L. Parke, Eve Clulow, Wei Huang, Namneet Kaur, Reinhard Karembera, Jacques-Olivier Gaudron, Xi Zhang, Matias Risaro, Jacob Tunesi, Henry Bourne, Marco Schioppo. 2026-06-04. Laser fractional frequency instability at $\mathbf{4\times 10^{-17}}$ with a room temperature optical reference cavity. https://doi.org/10.1364/optica.591175

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