Use of Bistable Centers in CdF2\text{}_{2} for Holographic Recording

It is shown that metastable centers in various semiconductors can be used for efficient hologram recording. This type of holographic materials has a very high dynamic range and sensitivity. Their major drawback for possible applications is low metastability temperature. This problem can be overcome by using CdF$\text{}_{2}$:Ga crystals, which exhibit metastability below 240 K. This material is suitable for writing thick and multiple holograms both in static and dynamic regimes

Photostriction of CdF2\text{}_{2}:In Crystals

Lattice relaxation accompanying phototransformation of In bistable centers from the ground, deep state to the shallow state in CdF$\text{}_{2}$ crystal has been measured with the use of scanning tunnelling microscope. It is shown that relatively small macroscopic changes of the crystal length in the order of 1.8×10$\text{}^{-6}$ accompany the phototransformation of In ions. Lattice expansion upon the influence of population of shallow donor levels in CdF$\text{}_{2}$ explains the observed small changes of lattice constant during the process

Light-Induced Gratings in CdMnTeSe:In Crystals

We show that DX-like centers in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{x}$:In crystal can be used in writing volume holographic gratings. The scattering efficiency is higher than 10% which proves the dispersive character of the light-induced gratings. Two different metastable centers with different lattice relaxation were found in the crystal. Measurements of the power dependence of the degenerate four-wave mixing scattering efficiency testify that both of these centers have negative U properties