Fe-doped BaTiO₃ Thin Films with Large Third-Order Nonlinear Optical Susceptibility

Iron doped BaTiO₃ epitaxial thin films were fabricated using the pulsed laser deposition technique. The target was an Fe/BaTiO₃ two-material physical assembly. The films were grown on MgO (100) substrates at 650°C. The crystalline property of the films was studied with x-ray diffraction. The result indicated that the Fe-doped BaTiO₃ films did not degrade their crystallinity at the dopant concentration of 4 mol%. The nonlinear optical properties of the films were determined using Z-scan method at the wavelength of 532 nm with laser duration of 10 ns. The real and imaginary parts of the third-order nonlinear susceptibility X³ were determined to be 3.67 x 10^-7 esu and 4.82 x 10^-8 esu, respectively.