Broadband photorefractive properties and self-pumped phase conjugation in Ce-SBN:60

Abstract

The first use of cerium-doped Sr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</inf> Ba <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</inf> Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> as a broadband self-pumped phase-conjugate mirror using internal reflection is reported. The phase-conjugate reflectivity at normal incidence ranged from two percent at 442 nm to seven percent at 515 nm and was zero at 633 nm. The electron-hole competition was found to be significant and had a wavelength dependence in one sample but not the other. The charge carrier density was <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sim 7 \times 10^{16}</tex> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and was wavelength in-dependent. The absorption coefficient ranged from 2 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> at the shorter the wavelengths to zero at longer wavelengths. The dispersion in the indexes of refraction was measured and the birefringence was -0.036. The sign of the dominant charge carriers was determined to be negative and the sign of the electrooptic coefficient, r <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</inf> , was positive. Using the above values, a wavelength dependent coupling coefficient has been determined. The experimental results indicate that the phaseconjugate reflectivity decreases at shorter wavelengths due to increased absorptive losses and experiences a threshold effect at longer wavelengths.