Second-harmonic imaging of ferroelectric domain walls

Abstract

Domain walls in periodically poled ferroelectric KTiOPO4 and LiNbO3 crystals are observed by making use of second-harmonic (SH) generation enhancement in the transition regions between neighboring domains. SH images of domain walls obtained with various samples for different polarization configurations are presented. The SH generation enhancement is found especially pronounced for the polarization of the SH radiation being perpendicular to the domain walls. The origin and selection rules for the contrast in SH images of domain walls are discussed. The results obtained suggest that the domain walls produce a deteriorating effect on SH generation by quasiphase matching.

Nonlinear magneto-optical diffraction from periodic domain structures in magnetic films

“…Recently, an analysis of the selection rules for the nonlinear polarization in ferroelectric crystals with DWs was made in Ref. 22. However, the authors of this article only took into account the nonlinear susceptibility tensor components which correspond to the domains.…”

“…Recently the second harmonic imaging of ferroelectric DWs was reported. [21][22][23] Nonlinear magneto-optical investigations of magnetic films and structures have several advantages in comparison to their linear equivalents. First, the nonlinear magnetooptical response allows us to obtain information about the magnetization at surfaces and buried interfaces.…”

Second-harmonic imaging of poled silica waveguides

“…SHG microscopy has successfully been applied for investigations of SON in periodically poled ferroelectric crystals, 6 domain structures in magnetic garnet films, 7 and ferroelectric domain walls. 8 In this letter, we present spatially resolved measurements of SHG in poled silica-based waveguides along with the conventional characterization of the LEO effect in these waveguides. Two sets of experiments were carried out in order to explore the potential of the SHG imaging technique.…”

Second-harmonic scanning optical microscopy of poled silica waveguides

“…2 Furthermore, starting with the first experiments on spatially resolved SHG from a dye monolayer, 3 SHG microscopy has evolved into a very useful characterization tool for inhomogeneous surfaces. It has recently been applied to imaging of periodically poled ferroelectric domains 4 and domain walls, 5 domain structures in epitaxially grown magnetic garnet films 6 and Langmuir-Blodgett monolayers, 7 and polar orientational distribution in thin polymer films. 8 Poled silicabased waveguides are yet another interesting objective for SHG microscopy that allows one to map spatial variations of second-order optical nonlinearities ͑SONs͒ and, thereby, to study the mechanisms of poling as well as to characterize the poled components.…”