| Series of Mg:Er:LiNbO3 crystals were grown by the Czochralski method. The growth and structure and the optical properties of the crystals were studied. In the part of crystal growth, the technological parameters of crystal growth were explored and optimized,the reasonable technological parameters were decided and the high quality crystals were grown. The crystals as-grown were processed by poling,cutting and polishing. X-ray powders diffraction of the crystals were carried out. The results showed that all the Mg:Er:LiNbO3 crystals hold the same lattice structures as the pure congruent LiNbO3 though the unit cell volume is changed. It demonstrated that Mg and Er ions enter lattice by the replacement of Li or Nb ions. Using infrared spectra and absorption spectra, the threshold concentration and location of Mg in doped LiNbO3 crystals were confirmed, and the location model was given. The threshold concentration of Mg is between 4mol% and 5mol% in doped LiNbO3 crystals. Before the doped concentration of Mg achieves its threshold Mg takes anti-site Nb (NbLi), and when the doped concentration of Mg over its threshold, Mg enters NbNb and LiLi sites at the same time. The photodamage resistance ability of those crystals was measured by the directly observing facula distortion method. It was shown that the photodamage resistance ability of Mg:Er:LiNbO3 crystals was two orders of magnitude higher than that of pure LiNbO3 crystal and was better than that of LiNbO3 crystal singly doped with Mg or Er. The frequency doubling properties of Mg:Er:LiNbO3 crystals were investigated. The results showed that the frequency doubling conversation efficiency of Mg(6mol%):Er(1mol%):LiNbO3 was measured to be about 38% and the phase matching temperature of the crystal was 98.2℃, its frequency doubling conversation efficiency has marked improve compare with that of pure LiNbO3 crystal, those demonstrate that Mg:Er:LiNbO3 crystal is excellent multiplier crystal material. |
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