Controlling the effective second-order susceptibility in random quadratic media.

We study systematically the effect of spatial disorder of ferroelectric domains in nonlinear media on the polarization properties of optical frequency conversion. Experimentally, different statistics of domain sizes are created using electric field poling at room temperature. We analyze the evolution of polarization properties of the second- and third-harmonic signals for each created statistic by determining the corresponding relative strength of non-zero components of the second-order susceptibility tensor, d24, d32 and d33. The relative strengths are labeled by means of the control parameter E on the characteristic P-E loop of the studied ferroelectric medium.