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Excited-state absorption in BaY 2 F 8 :<mml:math xmlns:…

1993; American Physical Society; Volume: 47; Issue: 17 Linguagem: Inglês

10.1103/physrevb.47.11001

1095-3795

Stéphan Guy, M.‐F. Joubert, B. Jacquier, Mohamed Bouazaoui,

Solid State Laser Technologies

Upconversion pumping with yellow cw and pulsed dye lasers was used to produce uv and blue light arising from deexcitation of the $^{4}$${\mathit{D}}_{3/2}$ and $^{2}$${\mathit{P}}_{3/2}$ states of ${\mathrm{Nd}}^{3+}$ ions in ${\mathrm{BaY}}_{2}$${\mathrm{F}}_{8}$:${\mathrm{Nd}}^{3+}$. Upconversion excitation occurs via sequential two-photon absorption, which was probed by the anti-Stokes emission dynamics and by a two-color laser experiment. An analysis of the steady-state populations as a function of pumping rates ${\mathit{R}}_{1}$ and ${\mathit{R}}_{2}$ for the two-step excitation is developed. When the excitation frequency is resonant with the $^{4}$${\mathit{F}}_{3/2}$${\ensuremath{\rightarrow}}^{4}$${\mathit{D}}_{3/2}$ excited-state absorption transition, the power dependence of the anti-Stokes fluorescence intensity, plotted on a logarithmic scale, shows a straight line with a slope of 1.8. This behavior is explained quite well by the model for a mean-excitation-power regime where the second step is 4 orders of magnitude more efficient than the ground-state absorption.