BGO Bi12GeO20 Bismuth Germanate Crystals Strong Electro Optical Effects

Bismuth germanate (Bi12GeO20) has high electro-optic coefficients (3.3 pm/V for Bi12GeO20) making it useful in nonlinear optics for building Pockels cells, and can also be used forphotorefractive devices for ultraviolet range.
The Bi12GeO20 crystals are piezoelectric, show strong electro-optical and acousto-optical effects, and find limited use in the field of crystal oscillators and SAW devices. Single crystal rods and fibers can be grown by floating zone process from a rod of mixture of bismuth oxide and germanium oxide.The crystals are transparent and brown colored.

The crystals of BGO and similar compounds BSO (Bi12SiO20, bismuth silicon oxide, sillenite) and BTO (Bi12GeO20), are photorefractive and photoconductive. BGO and BSO crystals are efficient photoconductors with low dark conductivity. They can be used in electro-optical applications, like optical PROM, PRIZ spatial light modulators, realtime hologramrecording, correlators, and systems for adaptive correction of ultrashort laser pulses, and in fiber optic sensors for electric and magnetic fields. Waveguide structures allow uniform illumination over wide spectral range. Thin film sillenite structures, which can be deposited e.g. by sputtering, have wide range of potential applications. BSO crystals are used in optically addressed spatial light modulators and in liquid crystal light valves.The optical activity of BTO is much smaller than of BGO and BSO.Unlike somewhat similar performingperovskites, sillenites aren't ferroelectric.

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