Features of randomized electric-field assisted domain inversion in   lithium tantalate
  We report on bulk and guided-wave second-harmonic generation via random Quasi-Phase-Matching in Lithium Tantalate. By acquiring the far-field profiles at several wavelengths, we extract statistical information on the distribution of the quadratic nonlinearity as well as its average period, both at the surface and in the bulk of the sample. By investigating the distribution in the two regions we demonstrate a non-invasive approach to the study of poling dynamics. 
Salvatore Stivala, Fabrizio Buccheri, Luciano Curcio, Roberto L.   Oliveri, Alessandro C. Busacca and Gaetano Assanto
physics.optics