Light absorption in undoped congruent and magnesium-doped lithium niobate crystals in the visible wavelength range

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2010-07, Vol.100 (1), p.109-115
• Main Authors: Schwesyg, J. R., Kajiyama, M. C. C., Falk, M., Jundt, D. H., Buse, K., Fejer, M. M.
• Format: Article
• Language: English
• Subjects: Boules; Chromium; Crystals; Engineering; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Iron; Lasers; Light absorption; Lithium niobates; Nonlinear optical crystals; Optical Devices; Optical materials; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Polarized light; Quantum Optics; Wavelengths
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-010-4063-1

Light absorption measurements of nominally undoped congruent lithium niobate crystals (CLN) as well as 5 mol% magnesium-oxide-doped lithium niobate (MgO:LN) crystals were performed in the light wavelength range of 350 to 800 nm. Absorption spectra reveal that—besides iron (Fe) impurities—chromium (Cr) impurities of less than 0.5 wt. ppm concentration contribute significantly to the total optical absorption in the CLN crystals with a maximum of 0.035 cm −1 around 500 nm. The axial distribution of Cr within a CLN boule is examined, revealing that the bottom part of the boule contains less Cr and therefore light absorption is reduced as well. In the case of the MgO:LN crystals, Cr impurities also contribute significantly to the total optical absorption, which is on the order of 0.025 cm −1 for ordinarily polarized light and 0.015 cm −1 for extraordinarily polarized light around 500 nm.