δ-BiB_3O_6:Pr~(3+): polymer nanocomposites deposited on substrates with silver nanoparticles for nonlinear optics

摘要

Composites containing nanocrystallites of novel rare earth doped borate δ-BiB_3O_6 and polyvinyl alcohol (PVA) polymer are reported. Experimental studies of the third-order nonlinear refractive index n_2, absorption coefficient β and second-order nonlinearity for δ-BiB_3O_6: Pr~(3+)(7.5 at.%) large-size nanocrystallites embedded into PVA polymer matrices and deposited on gallium-doped zinc oxide substrates modified with silver nanoparticles (Ag-NPs) using Z-scan technique and second harmonic generation (SHG) method were performed. The complex SHG and Z-scan measurements for different sizes of Ag-NPs were done. It was shown that the polymer composite of PVA containing particles of orthorhombic bismuth tri-borate doped with praseodymium (7.5 at.%) reveals optically nonlinear response. It was shown that the studied composites possess both coherent and non-coherent component of nonlinear optics. The Z-scan measurements were done with use of 5 ns Nd:YAG laser and the second harmonic generation was measured using the 25 ns Nd:YAG laser with frequency repetition about 10 Hz. The measurements showed that both second as well as third-order susceptibilities are sensitive to the sizes of the Ag-NPs. The obtained results confirm a principal role of the Ag-NPs in influencing the output susceptibilities.