Study on SHG property of Mg: Nd: LiNbO 3 crystal

Abstract

The congruent Nd (Nd: 0. 2 wt %): LiNbO₃ crystals doped with different concentration of MgO (MgO: 1, 3, 5,7mol %) have been grown by Czochralski method in air atmosphere. The crystals were made into samples after polarization, cut and polishing. The infrared absorption spectra of Mg: Nd: LiNbO₃ crystals were measured by using Fourier transform infrared spectrophotometer. The OH- absorption peaks of Mg (1mol %): Nd (0.2wt %): LiNbO₃ crystal and Mg (3mol %): Nd (0.2wt %): LiNbO₃ crystal located at about 3481cm^-1, while that of Mg (5mol %): Nd (0.2wt %): LiNbO₃ crystal and Mg (7mol %): Nd (0.2wt %): LiNbO₃ crystal shifted to 3536cm^-1. The mechanism of OH- absorption peak shifting was studied. The resistance to photodamage of Mg: Nd: LiNbO₃ crystals were measured by light spot distortion method. The results show that the photodamage threshold of Mg (5mol %) :Nd(0.2wt%):LiNbO₃ was the highest(9.0×104W/cm²) among the samples. The mechanism of the photodamage resistance ability of Mg:Nd:LiNbO₃ increasing was investigated. Using a Q adjustable Nd: YAG laser as pumping light, the second harmonic generation (SHG) properties, including the phase matching temperature and SHG conversation efficiency of Mg: Nd: LiNbO₃ were measured by 90 degree angle phase matching technology. The results showed that the SHG conversation efficiency of Mg (5mol %): Nd (0.2wt %): LiNbO₃ was the highest (52%) among the samples at 96°C.