Persistent spectral hole burning in deuteratedCaF2:Tm3+

We report spectral hole burning in the deuteride $\left({\mathrm{D}}^{-}\right)$ modified ${\mathrm{Tm}}^{3+}$ centers in ${\mathrm{CaF}}_2,$ where the hole burning mechanism is known to involve localized displacement of the ${\mathrm{D}}^{-}$ ions. Two main families of ${\mathrm{Tm}}^{3+}-{\mathrm{D}}^{-}$ centers are present; the $\mathrm{L}i$ centers yield spectral holes that have been measured to be fully persistent for 48 hours at liquid-helium temperatures, while spectral holes of the $\mathrm{M}i$ centers have a hole-recovery time constant of approximately 20–30 s. Hole widths vary from 18–40 MHz (full width at half maximum) for the different centers. Burn-down curves are in agreement with a simple and general model that takes into account the finite homogeneous linewidth but makes no other assumptions about the nature of the hole burning mechanism. The area of the spectral holes is found to be conserved after the sample temperature has been cycled to up to 70 K, while the hole profile is broadened by this process.