Frequency-stabilization to 6x10-16 via spectral-hole burning
Michael J. Thorpe, Tara M. Fortier, Matthew S. Kirchner, Till P. Rosenband, Lars Rippe
We demonstrate two-stage laser stabilization based on a combination of Fabry-Pérot and spectral-hole burning techniques. The laser is first pre-stabilized by the Fabry-Pérot cavity to a fractional-frequency stability of ςy(τ) -13. A pattern of spectral holes written in the absorption spectrum of Eu3+:Y2SiO5 serves to further stabilize the laser to ςy(τ) = 6 × 10-16. Measurements characterizing the frequency sensitivity of Eu3+:Y2SiO5 spectral holes to environmental perturbations suggest that they can be more frequency-stable than Fabry-Pérot cavities.