Scanning electro-optic microscopy of ferroelectric domain structure with a near-field fiber probe

Ferroelectric domain structure of barium titanate single crystals has been visualized using a fiber probe near-field microscope, combined with temporal modulation of optical signal provided by a sinusoidal electric field applied to the sample. We find that electro-optic contrast between the adjacent domains depends on the polarization of incident light not as strongly as in case of confocal microscopy. This fact is ascribed to presence of additional optical aberrations caused by the near-field arrangement confirmed by complicated approaching curve observed for the electro-optic signal. Surprising improvement in spatial resolution of the near-field electro-optic image comparing to the optical one has been observed in some cases, supporting the idea of surface-confined electro-optic modulation in qualitative agreement with the observed phenomenon. (C) 2011 American Institute of Physics. [doi:10.1063/1.3656731]