Optical properties of ferroelectric BaTiO3 (BTO) and paraelectric SrTiO3 (STO) multilayer structures were investigated
as a possible material choice for thin-film electro-optic devices. It has been demonstrated that dielectric properties can be
enhanced by optimizing the stacking periodicity of BTO-STO superlattices, and in this work, it was studied how the
shifts in permittivity are transferred to the optical properties. BTO-STO superlattices with stacking periodicity varying
between 27 Å and 1670 Å were grown on MgO substrates by pulsed laser deposition. In x-ray diffraction patterns,
periodic satellite peaks were observed indicating the formation artificial superlattices. The evolution of electro-optic
response with varying stacking periodicity was analyzed by ellipsometric transmission method. The electro-optic
response reached a maximum at a stacking periodicity of 105 Å corresponding the individual layer thickness of 13 unit
cells. The suitability of superlattices, and also single layer BTO thin films, in planar optical devices were evaluated by
fabricating and characterizing Mach - Zehnder waveguide modulators.
We examine the luminescent properties of cerium-doped yttrium aluminum garnet (Ce:YAG)
under cathodoluminescence. The cerium emission is strongly affected by the presence of intrinsic
defects it the crystal. We show that a model based on non-radiative energy transfer is compatible
with the results obtained from cathodoluminescence exreriments.