21 research outputs found
Microstructure of TiN coatings synthesized by direct pulsed Nd:YAG laser nitriding of titanium: Development of grain size, microstrain, and grain orientation
Strain-induced second-harmonic generation in pseudocubic Ba<sub>0.48</sub>Sr<sub>0.52</sub>TiO<sub>3</sub> thin films
We report the observation of a strong second-order nonlinear optical response from epitaxial Ba<sub>0.48</sub>Sr<sub>0.52</sub>TiO<sub>3</sub> thin films grown on MgO(001) by magnetron sputtering. The result is unexpected since the crystal structure of Ba<sub>0.48</sub>Sr<sub>0.52</sub>TiO<sub>3</sub> is centrosymmetric under ambient conditions. A second-order nonlinear susceptibility d<sub>33</sub> as large as 11 pm/V at a fundamental wavelength of 1.064 μm is observed in a 300 Å thick film. By studying a series of films with different strains, induced by a film-substrate lattice mismatch, we conclude that the resulting tetragonal distortion, presumably accompanied by a loss of inversion symmetry, is responsible for the second-harmonic generation. © 2000 American Institute of Physics