Absolute and Relative Stability of an Optical Frequency Reference Based on Spectral Hole Burning in Eu~(3+):Y_2SiO_5

摘要

We present and analyze four frequency measurements designed to characterize the performance of an optical frequency reference based on spectral hole burning in Eu~(3+):Y_2SiO_5. The first frequency comparison, between a single unperturbed spectral hole and a hydrogen maser, demonstrates a fractional frequency drift rate of 5 X 10~(-18) s~(-1). Optical frequency comparisons between a pattern of spectral holes, a Fabry-Perot cavity, and an Al~+ optical atomic clock show a short-term fractional frequency stability of 1 × 10~(-15)(τ)~(1/2) that averages down to 2.5~(+1.1)_(-0.5) × l0~(-16)at (τ) = 540 s (with linear frequency drift removed). Finally, spectral-hole patterns in two different Eu~(3+):Y_2SiO_5 crystals located in the same cryogenic vessel are compared, yielding a short-term stability of 7 × 10~(-16)τ~(-1/2) that averages down to 5.5~(+1.8)_(-0.9) × 10~(-17) at (τ) = 204 s (with quadratic frequency drift removed).