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arXiv · 0807.2582

Measurement of fundamental thermal noise limit in a cryogenic sapphire frequency standard using bimodal maser oscillations

Karim Benmessai·Daniel Lloyd Creedon·Michael Edmund Tobar·Pierre-Yves Bourgeois·Yann Kersale·Vincent Giordano
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Abstract

We report observations of the Schawlow-Townes noise limit in a cryogenic sapphire secondary frequency standard. The effect causes a fundamental limit to the frequency stability, and was measured through the novel excitation of a bimodal maser oscillation of a Whispering Gallery doublet at $12.04 GHz$. The beat frequency of $10 kHz$ between the oscillations enabled a sensitive probe for this measurement of fractional frequency instability of $10^{-14}τ^{-1/2}$ with only 0.5 $pW$ of output power.

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Karim Benmessai, Daniel Lloyd Creedon, Michael Edmund Tobar, Pierre-Yves Bourgeois, Yann Kersale, Vincent Giordano. 2008-07-16. Measurement of fundamental thermal noise limit in a cryogenic sapphire frequency standard using bimodal maser oscillations. https://doi.org/10.1103/physrevlett.100.233901

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