Frequency-stabilization to 6x10^-16 via spectral-hole burning

We demonstrate two-stage laser stabilization based on a combination of Fabry- Perot and spectral-hole burning techniques. The laser is first pre-stabilized by the Fabry-Perot cavity to a fractional-frequency stability of sigma_y(tau) < 10^-13. A pattern of spectral holes written in the absorption spectrum of Eu3+:Y2SiO5 serves to further stabilize the laser to sigma_y(tau) = 6x10^-16 for 2 s < tau < 8 s. Measurements characterizing the frequency sensitivity of Eu3+:Y2SiO5 spectral holes to environmental perturbations suggest that they can be more frequency stable than Fabry-Perot cavities

Relating localized electronic states to host band structure in rare-earth-activated optical materials

The energies of the rare-earth ions' electronic states relative to the host band states in optical materials were discussed. Resonant electron photoemission spectroscopy (REPS) was used. Results provide a model to describe the rare earth binding energies in optical materials with two parameters such as constant shifts and dependence of ionic radius.link_to_subscribed_fulltex