arXiv:1307.5355 · Physical Review Letters
Absolute and Relative Stability of an Optical Frequency Reference Based on Spectral Hole Burning in Eu3+:Y2SiO5
David R. Leibrandt, Michael J. Thorpe, C. W. Chou, Tara M. Fortier, Scott A. Diddams, Till Rosenband
Abstract
We present and analyze four frequency measurements designed to characterize the performance of an optical frequency reference based on spectral hole burning in ${\mathrm{Eu}}^{3+}\mathrm{\text{:}}{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$. The first frequency comparison, between a single unperturbed spectral hole and a hydrogen maser, demonstrates a fractional frequency drift rate of $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$. Optical frequency comparisons between a pattern of spectral holes, a Fabry-P\'erot cavity, and an ${\mathrm{Al}}^{+}$ optical atomic clock show a short-term fractional frequency stability of $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}{\ensuremath{\tau}}^{\ensuremath{-}1/2}$ that averages down to ${2.5}_{\ensuremath{-}0.5}^{+1.1}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ at $\ensuremath{\tau}=540\text{ }\text{ }\mathrm{s}$ (with linear frequency drift removed). Finally, spectral-hole patterns in two different ${\mathrm{Eu}}^{3+}\mathrm{\text{:}}{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ crystals located in the same cryogenic vessel are compared, yielding a short-term stability of $7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}{\ensuremath{\tau}}^{\ensuremath{-}1/2}$ that averages down to ${5.5}_{\ensuremath{-}0.9}^{+1.8}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$ at $\ensuremath{\tau}=204\text{ }\text{ }\mathrm{s}$ (with quadratic frequency drift removed).