Nonlinear Optical Characteristics of BSO and BGO Photorefractive Crystals in Visible and Infrared Ranges

Abstract

Nonlinear refraction, nonlinear absorption and optical limiting in photorefractive crystals Bi12SiO20(BSO) and Bi12GeO20(BGO) at the wavelengths of 1064 and 532 nm were investigated. It was shown that both BSO and BGO crystals possess by positive nonlinear refraction in two investigated spectral ranges (n2BSO=(2.5 ± 0.5)× 10−12 esu, n2BGO=(6.3 ± 1.3)× 10−12 esu at λ equals 1064 nm; n2BSO=(4.4 plusmn; 0.9)× 10−12 esu, n2BGO=(7.4 ± 1.5)× 10−12 esu at λ= 532 nm). The nonlinear absorption was due to three-photon absorption at the wavelength of 1064 nm (β(3ω)BSO=(2.5 ± 0.8)× 10−20cm3W−2, β(3ω)BSO=(4.4 ± 1.3)× 10−20cm3W−2) and two-photon absorption at the wavelength of 532 nm (β(2ω)BSO=(2 ± 0.4)× 10−9cm W−1, β(2ω)BGO=(3.7 ± 0.7)× 10−9cm W−1).