Novel features of white light emission observed in transparent Cr-doped YAG ceramics

The laser-induced white light emission (LIWE) is a phenomenon based on multiphoton absorption of NIR light and subsequent emission in the visible range. The LIWE can be achieved from the samples placed in vacuum (10 −2 mbar) excited by focused near infrared laser beam [1] . LIWE is a threshold phenomenon that strongly depends on the excitation power density. To explain this phenomenon, the following models have been proposed: black body radiation, photon avalanche, electron-hole recombination, inter valence charge transfer, etc [2] . Except black body radiations, all these models were based on multiphoton absorption of the laser light with further transfer of free electrons to the conduction band. However, due to the lack of experimental data, the origin of LIWE is under discussion. In this paper, the model for describing LIWE is extended.