SHG microscopy

As of shortly the profiling of ferroelectric domains in bulk of ferroelectrics in non-destructive way was an open demand. A modern optical technique has recently been developed by utilizing a special parametric process in nonlinear optics. The promising approach is based on the generation of second-harmonic signals in non-paraxial directions, satisfying a phase-matching condition known in literature as Cerenkov-type phase-matching condition. Second harmonic signals are expected non-collinearly under a certain angle defined by the material dispersion. One of the benefits here is that the matching condition is automatically fulfilled at domain walls or Χ(2) modulation. This feature paved the way to construct a tool able to detect the domains, called Cerenkov-type second-harmonic microscopy. The concept differs from that used in the conventional second-harmonic generation in which the phase mismatch has to be less than zero for second-harmonic generation in the forward direction only. We utilize Cerenkov SH microscopy to investigate different Χ(2) structures in its static and dynamic states, enabling perfect tailoring of ferroelectric domains and similar Χ(2) structures for diverse photonic applications in the linear as well as the nonlinear regimes.