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.