PERSISTENT SPECTRAL HOLE-BURNING SPECTROSCOPY OF THE T-1U[-A(1G) (690NM) LINE IN THE CAF2-SM2+ SYSTEM

We use persistent spectral hole burning to simultaneously measure the homogeneous linewidth and the frequency shift of the lowest one-photon allowed transition of the CaF2:Sm2+ system. A nonmonotonous temperatu re dependence is observed for the frequency shift. Our measurements fo r both width and shift indicate that the dominant dephasing process is a direct one-phonon absorption process, the (acoustic) phonon frequen cy being similar to 45 cm(-1). This means that the Sm2+ ion possesses a level similar to 45 cm(-1) above the T-1u level. Our discussion sugg ests that this is the T-2u level. The inhomogeneous distribution is Lo rentzian and its width and position depend on the Sm3+ concentration ( the Sm3+-F- complexes acting as point defects) exactly as predicted by theory. [S0163-1829(98)00842-X].