Visualization of ferroelectric domains in boracite using emission of terahertz radiation

Abstract

We report on the emission of terahertz radiation by irradiation of femtosecond laser pulses in non-centrosymmetric paraelectric and ferroelectric phases of Co3B7O13I boracite.The Generation of the terahertz waves in both phases is caused by optical rectification via a second-order nonlinear optical effect. In the ferroelectric phase, we successfully visualized ferroelectric domains by analyzing the polarization state of the terahertz wave radiated from the crystal. In a large area of the crystal (500 × 500 m 2 ), the observed polarization vector of the radiated terahertz wave was tilted from directions of spontaneous polarization, i.e., 100, 010 , and 001 in cubic setting, which can be explained by the presence of a ferroelectric 90 domain wall of the 101 plane. 1. Second-order nonlinear optical susceptibility in paraelectric phase

Terahertz Radiation by Subpicosecond Magnetization Modulation in the Ferrimagnet LiFe5O8

“…Furthermore, the direction of the magnetization can be determined from the electric-field direction of the radiated terahertz wave evaluated with the vector-imaging technique illustrated in Figure a. This scheme has been used to visualize the ferroelectric domains and polarization directions in several kinds of ferroelectrics. − …”

“…The sample holder was attached to a two-dimensional moving stage and moved along the X - and Y -axes. Further experimental details are described in refs − .…”

Terahertz Radiation Imaging of Ferroelectric Domain Topography in Room-Temperature Hydrogen-Bonded Supramolecular Ferroelectrics

“…Great research activities have therefore developed various methods for visualization of ferroelectric domains . Examples are X-ray topography, scanning electron microscopy, piezoelectric force microscopy (PFM), electro-optic imaging microscopy, Raman confocal microscopy, second-harmonic-generation microscopy (SHG), , near-field scanning optical microscopy, and emission of terahertz waves. − …”

Sub-wavelength terahertz imaging through optical rectification

“…To our knowledge, the idea of THz imaging through OR was only published by a Japanese team 22 – 24 , in view of observing ferroelectric domains and especially domain walls in supramolecular ferroelectrics. Impressive images were obtained, but microscopy was not the main goal of this study.…”