Fluorescence reabsorption and its effects on the local effective excitation lifetime

James Keaveney

Yukio Inoue, Ryuji Iwazaki, Hirokazu Hori +1 more

The effects of the reabsorption of radiation on the lifetime of the Cs 72P3/2 level were measured from the decaying waveform of fluorescence under various experimental conditions. Reabsorption does not have any influence on the lifetime when the experimental condition satisfies k 0 L<1, where k 0 is the peak absorption coefficient and L is the reabsorbing path length. A theoretical calculation based on a simple model agrees with the experimental results.

Z. Ficek, R. Tanaś

I. G. Kisialiou

Light reabsorption and radiation trapping can noticeably distort fluorescence decay in solid-state laser gain media with a partial overlap of absorption and emission bands. In this paper, the upper-state lifetime measurements in laser materials by the method of transient gratings are discussed. A theoretical model for description of reabsorption in a thin layer is developed. It is shown that under certain conditions reabsorption has no effect on the transient time of refractive index grating and thus the true upper-state lifetime can be measured. Some experimental results confirming effectiveness of the technique are presented.

Leszek Kułak, R. Twardowski, Czeslaw Bojarski

Francesco Caminati, Giovanni Cittadino, Eugenio Damiano +2 more

In the perspective of building a solid state cryocooler based on optical refrigeration, it is strategic to develop high purity crystals and to have a full understanding of the mechanisms that can reduce cooling efficiency. In this paper we highlight two loss mechanisms that can hinder the optical refrigeration performance of a Yb:YLF monocrystal: the presence of impurities and fluorescence reabsorption. We show how the presence of impurities can be inferred by measuring the mean lifetime of the Yb optical transition. We measure how a few ppms of other rare earth ions can be detrimental for optical refrigeration by exciting a cooling Yb:YLF sample with two laser sources. We also report the first practical demonstration of the negative effect of fluorescence reabsorption on the cooling performance.