Some Optical Properties of LiNbO3:Gd3+(0.003):Mg2+(0.65 wt %) Single Crystal: A Promising Material for Laser Radiation Conversion

A nonlinear optical double-doped single-crystal LiNbO3:Gd:Mg (Gd concentration is 0.003, Mg—0.65 wt % in the crystal) has been researched by several methods: laser conoscopy, photoinduced light scattering (PILS), spectroscopy, and Raman scattering. The crystal shown to have no photorefraction effect a high uniformity. Fine features of structure studied via spectra. Spectra registered first second orders, they excited visible (532 nm) near-IR (785 lasers. Registered spectra fundamental vibrations lattice A1(TO,LO)- E(TO,LO)-type symmetry located range 150–900 cm−1. number low-intensity bands 900–2000 cm−1 region determined correspond second-order spectrum. These are polarized appear only certain polarization-scattering geometries. They spectrum radiation, but their intensity much lower than those Oxygen-octahedral MeO6 clusters our case can contain Li, Nb, Gd, or Mg Me site. slightly distorted compared with similar nominally pure LiNbO3 crystal. It established that value R = [Li]/[Nb] ≈ 1. Such ratio usually characterizes stoichiometric