Micro-spectroscopic characterization of ferroelectric domain structures in Yb3+:LiNbO₃ prepared by electron beam writing

摘要

Sub-micrometer inverted domains in Yb3+ doped bulk LiNbO3 crystals are reported by using direct electron beam writing (DEBW) as a tool to reverse the spontaneous polarization in a two dimensional geometry. The effect of electron bombardment within the domain inversion process is analyzed at the micrometer scale by combining spatially resolved confocal Raman, Fluorescence and Second Harmonic Generation (SHG) imaging techniques. The obtained results not only confirms the feasibility of DEBW on the inversion procedure -the linear and nonlinear optical properties of the system remain unaltered after the process, but they also show that the slight structural changes associated with the polarization reversal in LiNbO3 are independent on the employed switching mechanism. The possibility of obtaining complementary non-destructive spectroscopic images of domains is also shown. Together, the results highlight the outstanding opportunities offered by confocal spectroscopy as a non invasive tool to probe the interaction between intrinsic defects and ferroelectric domain reversal structures in LiNbO3. Additionally, they provide valuable information to further decrease the size and distance between adjacent inverted domains in a solid state system in which, IR laser action, self-frequency conversion processes and laser tunability have been demonstrated.