Semiconductor CdF<sub>2</sub>:Ga and CdF<sub>2</sub>:In Crystals as Media for Real-Time Holography

• Main Authors: Alexander E. Angervaks, Alexander S. Shcheulin, Alexander I. Ryskin
• Format: Article
• Language: English
• Published: MDPI AG 2012-05-01
• Series: Materials
• Subjects: cadmium fluoride; bistable centers; photoinduced metastable state; holographic grating decay; real-time holography; dynamic correction of wavefronts and optical images; holographic correlator
• Online Access: http://www.mdpi.com/1996-1944/5/5/784

Monocrystalline cadmium fluoride is a dielectric solid that can be converted into a semiconductor by doping with donor impurities and subsequent heating in the reduction atmosphere. For two donor elements, Ga and In, the donor (“shallow”) state is a metastable one separated from the ground (“deep”) state by a barrier. Photoinduced deep-to-shallow state transition underlies the photochromism of CdF<sub>2</sub>:Ga and CdF<sub>2</sub>:In. Real-time phase holograms are recorded in these crystals capable of following up optical processes in a wide frequency range. The features of photochromic transformations in CdF<sub>2</sub>:Ga and CdF<sub>2</sub>:In crystals as well as holographic characteristics of these media are discussed. Exemplary applications of CdF<sub>2</sub>-based holographic elements are given.