Abstract

Čerenkov-type second-harmonic microscopy has recently attracted much attention because of its ability to resolute the ferroelectric domain walls even in disordered crystals. As reported in [1], ferroelectric domain structures are from a few hundred of nanometers to several microns thick and they can be resolved and visualized in both two and three dimensions. In general, Čerenkov-type second-harmonic emission is one of the most interesting non-collinear parametric patterns in far-field because of its spatial properties and spectral dependencies [2]. Much efforts have been devoted to investigate the physical origin of this phenomena and its relation to the Fourier spectrum of the domain structures [3]. However, it has been proved that the sharp modulation of the χ² nonlinearity constitutes a sufficient condition for the emission of Čerenkov second harmonic in bulk materials [4]. So its high sensitivity to the ferroelectric domain walls offers an excellent tool to monitor the ferroelectric domain growth and switching, even in bulk and in three dimensions. Such a dynamic was until now a challenge to be visualized in real time.

© 2015 IEEE