Nonlinear Disorder Mapping Through Three-Wave Mixing
  We implement a simple and powerful approach to characterize the domain distribution in the bulk of quadratic ferroelectric crystals via far-field second-harmonic spectroscopy. The approach is demonstrated in a lithium tantalate sample with periodic electric field poling and random mark-to-space ratio. 
Alessia Pasquazi, Alessandro Busacca, Salvatore Stivala, Roberto   Morandotti and Gaetano Assanto
physics.optics