SBN thin film growth by pulsed laser deposition and study of nonlinear optical properties

Abstract

Strontium barium niobate (SrxBa1−xNb2O6) thin films were grown by PLD and characterized as to their structure, composition, and both linear and nonlinear optical properties. Attempted composition of very nearly x'0.61 was achieved, as shown within experimental error of RBS and PIXE techniques. Films deposited with high growth rates and at 700°C substrate temperature resulted polycrystalline on (001)-cut MgO and amorphous on fused silica, while those grown on MgO at lower growth rates were very well oriented with the substrate. A considerable blue shift in the absorption band edge was observed for the disordered SBN:61 films, compared to that for bulk SBN:61 crystal. A broad luminescence band was observed to occur, similar to that for bulk SBN. Degenerate four-wave-mixing techniques were used to study the nonlinear optical response of the amorphous films. A considerable enhancement, by 2 orders of magnitude, of the third order nonlinear susceptibility χ(3) in transverse alignment was found to occur with respect to bulk values. A significant squeezing of the coherent response signal was observed in the SBN films.