ON THE SHIFTING OF OPTICAL-TRANSITION FREQUENCIES IN RARE-EARTH DOPED INSULATORS BY RESONANT OPTICAL-EXCITATION

Photon echo experiments, conducted in cryogenic Eu3+ : Y2O3, indicate that resonant excitation of Eu3+ ions results in a slight shifting of the excited ion's optical transition frequency. This effect is a direct analog of the effect known in NMR as instantaneous diffusion. One explanation for the existence of excitation-induced optical frequency shifts is to postulate a state-dependent permanent electric-dipole associated with the Eu3+ sites. Studies of excitation-mediated frequency shifts can be expected to shed light on this hypothesis and to influence the interpretation of both time- and frequency-domain optical studies of relaxation dynamics since both dephasing rates and linewidths can be affected by the shifts. © 1990.