Luminescence

P. T. Landsberg

Serge E. Zelensky, E-mail: zele@univ.kiev.ua

This paper deals with the methodology of laser-induced luminescence at high excitation levels.For a case when a photodetector collects integral (over the volume) luminescence power, a method is proposed for processing the experimentally-measured luminescence power and optical transmittance as some functions of the incident laser power.The method is based on the analysis of relative increments of luminescence and transmitted laser power.Considered are two examples of mechanisms of non-linear laserinduced luminescence, namely: saturated molecular luminescence and luminescence excited via two-photon absorption.

Yanli Mao, Fei Ding, Changshun Wang +2 more

Cooperative luminescence phenomenon of Yb:YAG crystals was studied. Up-converted blue luminescence was obviously observed in Yb:YAG under excitation in the near-infrared region with a wavelength 940 nm. Experimental evidence was provided by the fact that the intensity of 498 nm luminescence shows a quadratic dependence on excitation power, and the intensity of blue luminescence increased with the increase in Yb ion concentration. It is concluded that this luminescence is due to a cooperative process resulting from a strong interaction of Yb ions. The cooperative luminescence is possiblely assigned to the strong interaction of 4f(13) electrons and neighboring Yb3+ ions in a covalent host lattice such as YAG. Theoretical cooperative luminescence spectrum was calculated.

B. Ullrich, Takayoshi Kobayashi

Recently, we have discovered that the excitation of thin CdS films with the 514.5 nm line causes an all-optical bistable luminescent emission in the near infrared part of the spectrum. A first insight in mechanism and origin of all-optical bistability in luminescence of semiconductors is presented. We show that the initial and final states of the bistable luminescence are determined by the thermal properties of the luminescence intensity of the thin CdS film. However, during the bistable switch of the luminescence thermal effects and electronic ones take place. Thus, all-optical bistability in luminescence is a thermally induced electronic bistability.