Growth, microstructure and optical characteristics of doped LiNbO3:Gd and LiNbO3:Cu:Gd lithium niobate crystals

• Published in: Optical materials Vol. 135; p. 113241
• Main Authors: Palatnikov, M.N., Sidorov, N.V., Pyatyshev, A. Yu, Sverbil, P.P., Teplyakova, N.A., Makarova, O.V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-01-2023
• Subjects: Copper; Doping; Gadolinium; Lithium niobate; Optical properties; Gadolinium; Lithium niobate; Copper; Optical properties; Doping
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2022.113241

Double- and single-doped lithium niobate (LN) crystals were grown by Czochralski at air from platinum crucibles: sample 1 ([Cu] = 0.57, [Gd] = 0.07 wt%), sample 2 ([Cu] = 0.041, [Gd] = 0.076 wt%), sample 3 ([Gd] = 0.003 wt%), sample 4 ([Gd] = 0.01 wt%), sample 5 ([Gd] = 0.05 wt%) and sample 6 ([Gd] = 0.26 wt%). Macro- and microstructure of as-grown LiNbO3:Cu:Gd and LiNbO3:Gd crystals have been studied by optical microscopy. Laser conoscopy, photoinduced light scattering (PILS) and optical spectroscopy have studied optical transmission, optical uniformity and photorefraction in LN crystals. Such a composition have been determined for a four-component system Li2O–Nb2O5–CuO—Gd2O3, at which a highly compositionally and optically uniform LiNbO3:Cu:Gd crystal (sample 2, [Cu] = 0.041, [Gd] = 0.076 wt%) can be grown. Raman spectra in 180-grade scattering geometry have determined conditions for the excitation of transverse and longitudinal polar modes during Raman scattering in LiNbO3:Cu:Gd crystals. A great increase in 175 and 603 cm−1 Raman bands intensities has been detected at an increase in copper concentration; it has been explained as a manifestation of photorefractive effect.
•2 LiNbO3:Cu:Gd and 4 LiNbO3:Gd crystals were studied.•Gd strongly suppresses, Cu strongly increases photorefractive response of LN crystals.•Defective structure of LN:Cu:Gd is different from that of LN:Gd.•LN:Cu:Gd crystals are anomalously biaxial.•Addition of Cu to LN:Gd changes domains type and crystallization conditions.