TRANSIENT HOLE-BURNING AND FREE INDUCTION DECAY IN LOW-TEMPERATURE IMPURITY-ION CRYSTALS - APPLICATION TO OPTICAL DEPHASING AND SPECTRAL DIFFUSION IN RUBY

Transient hole burning (THB) and free induction decay (mo) in low-temp erature impurity-ion crystals are studied consistently using the model of two jump processes U-t = U-1(t) + U-2(t) (the random telegraph pro cess U-1(t) and the Kubo-Anderson jump process U-2(t) with Lorentzian distribution of possible values) characterized by essentially differen t correlation times tau(c1) much less than tau(c2) and distribution wi dths sigma(1) much less than sigma(2) for the impurity-ion optical tra nsition frequency fluctuations U-t Of different time scales resulting from frequent bulk host spin flip-flops and slow frozen core spin dyna mics. For short pump/probe pulse widths T and short delay times tau(d) between the pump and probe pulses (T, tau(d) much less than v(2)(-1)) , the calculated hole shape is narrow with the hole width being determ ined by the U-1(t) process characteristics only. The hole width in thi s case coincides with the calculated mo rate. For large pump powers, t he theory predicts the nutational oscillations in the narrow hole shap e which are smoothed out due to the averaging over the inhomogeneous d istribution of an impurity-ion optical transition frequencies and over the Gaussian distribution of the pump Rabi frequencies in the pump be am profile. For long delay times tau(d) greater than or equal to v(2)( -1), the U-2(t) process jumps spread the hole into a wide Lorentzian w ith the half-width 2 sigma(2), while the mo rate remains practically u naffected by the slow process. The theory is shown to fit well the exp erimental data by A. Szabo et al. on THE and FID in ruby under low and high magnetic held supposing the RT fluctuations U-1(t) to be rather slow (sigma(1)(2)/v(1)(2) approximate to 0.5).