Refractive index database

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Optical constants of Bi12GeO20 (Bismuth germanate, BGO)
Simon et al. 1997: n 0.45–0.70 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]



21 °C


M. Simon et al.. Refractive indices of photorefractive bismuth titanate, barium-calcium titanate, bismuth germanium oxide, and lead germanate, Phys. Stat. Sol. 159, 559-562 (1997)


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Bismuth germanium oxide, Bi12GeO20 (BGO)

Bi12GeO20, also abbreviated as BGO but distinct from bismuth germanate, is a bismuth germanium oxide compound known for its fascinating electro-optic and acousto-optic properties. It is primarily used in applications requiring high-speed modulation and deflection of light, such as in Q-switching of lasers, optical data storage, and light modulation for telecommunications. The crystal structure of Bi12GeO20 contributes to its large electro-optic and acousto-optic coefficients, making it one of the preferred materials for devices that require fast and efficient control of optical signals. It is also used in piezoelectric applications and has been explored for its potential as a photorefractive material. The crystal can be grown using techniques like the Czochralski method, and its optical properties can be fine-tuned through doping or altering growth conditions. Although it is less common than other electro-optic materials like lithium niobate, its unique combination of properties, such as high optical damage threshold and good thermal stability, make it a valuable material for specialized optical applications.

Other name

  • Bismuth germanate

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