Exceptionally large third-order optical susceptibility in Ag:SrBi2Nb2O9 composite films

Abstract Thin films of SrBi 2 Nb 2 O 9 with and without the inclusion of Ag nanocrystals were prepared on MgO (001) substrates by alternative pulsed laser ablation of SrBi 2 Nb 2 O 9 ceramic and Ag metal in a nitrogen atmosphere. The size of the Ag nanocrystals can be brought down to ca. 5.0 nm, as revealed by transmission electron microscopy and X-ray diffraction. We measured the third-order susceptibility χ (3) of the deposits by single beam z -scan technique at a wavelength of 532 nm. It is found that SrBi 2 Nb 2 O 9 is an effectively nonlinear optical medium, exhibiting a very large χ (3) . With the inclusion of Ag nanocrystals the χ (3) was nearly doubled ( Reχ (3)  = 8.052 × 10 − 7  esu, and Imχ (3)  = − 1.717 × 10 − 7  esu), which comes very close to the maximum value available in the current time. This indicates that the Ag:SrBi 2 Nb 2 O 9 composite structure can be an excellent candidate for nonlinear optical applications. A general approach for further enhanced third-order susceptibility by tailoring the dielectric constant of the metal inclusion is briefly discussed.