Four-Wave-Mixing Spectroscopy of Cr-Doped Garnet Crystals

摘要

The characteristics of the four-wave-mixing signal of Cr(3+)ions were measuredfor host crystals of Gd3Sc2Ga3O12, Gd3Ga5O12, (Gd,Ca)5(Ga,Mg,Zr)2Ga5O12, and La3Lu2Ga3O12. Signal strengths and decay times were measured as functions of laser-beam crossing angles and temperature. The results are used to determine the properties of radiationless decay and energy-transfer processes in these samples. By comparing the characteristics of the 4T2(2)E radiationless relaxation process among these and previously investigated Cr(3+)-doped laser crystals, it is shown that the ratio of the intersystem crossing relaxation rate to the internal conversion relaxation rate decreases as the strength of the crystal field of the host material decreases. The properties of energy migration among the Cr(3+) ions in the different host materials is found to depend on the average separation of the Cr(3+) ions, the strength of the crystal field, and the electron phonon interactions. Keywords: Reprints. (js)