Persistent and transient spectral hole burning in Pr3+- and Eu3+-doped silicate glasses

Abstract

Persistent and time-resolved transient holes were burnt into the D213H4 transition of Pr3+ and the D057F0 transition of Eu3+ in silicate glasses. The holewidths were studied as a function of burning-fluence density, wavelength, and temperature between 0.4 and 12 K. Transient holes arising from optical pumping of ground-state nuclear hyperfine levels were found for both ions at T<3 K. Their lifetime decreases with increasing temperature. They are accompanied by symmetrically placed antiholes. For Eu3+, two pairs of antiholes were found which are attributed to the two europium isotopes, Eu151 and Eu153. For Pr3+, an additional mechanism leading to persistent hole burning dominates above 3 K. The holewidth follows a T(1.30.1) dependence for Pr3+ and a T(1.00.1) dependence for Eu3+. The temperature dependence is the same as that of the contribution of the two-level systems to the specific heat measured on the same samples and in the same temperature range. The quadrupole splittings of the F07 ground state and the crystal-field splittings of the F17 and F27 levels of Eu3+ as a function of excitation wavelength indicate that the strength of the noncubic component of the crystal field varies monotonically for excitation across the D057F0 absorption band, falling to zero at the long-wavelength edge. The hole width shows a similar variation with excitation frequency. No influence of the experimental time scale on the hole width was detected for either sample between 10-2 and 102 s. © 1994 The American Physical Society.