PHOTON-ECHO MEASUREMENTS ON THE TRIVALENT THULIUM ION

Photon-echo measurements are reported for the trivalent thulium ion, which differs from all other rare-earth ions in having a single isotope of nuclear spin 1/2. Echo decays on the H-3(6)(1) <-- --> H-3(4)(1) transition of LaF3:Tm3+ and YAG:Tm3+ were magnetic-field dependent at 1.5 KU, showing that the dephasing originates from spin fluctuations of nuclei in the host crystals. Coherence times in the range of 7 to 100 mus were measured, corresponding to homogeneous linewidths of tens of kilohertz. The echo decays were nonexponential, providing evidence for spectral diffusion that is due to a distribution of F-19 and Al-27 nuclear spin-flip times in the respective hosts.