Optical decoherence and persistent spectral hole burning in Tm3+:LiNbO3

We report studies of decoherence and spectral hole burning for the 794 nm optical transition of thulium-doped lithium niobate. In addition to transient spectral holes due to the H-3(4) and F-3(4) excited states of Tm3+, persistent spectral holes with lifetimes of up to minutes were observed when a magnetic field of a few hundred Gauss was applied. The observed anti-hole structure identified the hole burning mechanism as population storage in the Tm-169 nuclear hyperfine levels. In addition, the magnetic field was effective in suppressing spectral diffusion, increasing the phase memory lifetime from 11 mu s at zero field to 23 mu s in a field of 320 Gauss applied along the crystal's c-axis. Coupling between Tm3+ and the Li-7 and Nb-93 spins in the host lattice was also observed and a quadrupole shift of 22 kHz was measured for Li-7 at 1.7 K. A Stark shift of 18 kHz cm/V was measured for the optical transition with the electric field applied parallel to the c-axis. (c) 2009 Elsevier B.V. All rights reserved.