Fe/SrBi2Nb2O9 composite thin films with large third-order optical nonlinearities

Abstract

Fe/SrBi 2 Nb 2 O 9 composite thin films have been fabricated on fused quartz substrates at room temperature by RF magnetron sputtering technique. XRD result demonstrated that the Fe and SrBi 2 Nb 2 O 9 (SBN) were well crystallized. Atomic force microscope (AFM) analysis indicated that the composite films have less rough surface. Their chemical composition was characterized by X-ray fluorescence spectrometer. The optical absorption of the films were measured from 300 nm to 800 nm, and the absorption peak was observed near 500 nm due to the surface plasma resonance of Fe particles. The nonlinear optical properties of Fe/SBN thin films were determined using z-scan method at a laser wavelength of 532 nm with laser duration of 25 ps, closed to the resonance frequency. z-Scan results show that Fe/SBN composite films exhibit a great picosecond nonlinear optical response, and the real and imaginary parts of the third-order nonlinear susceptibility ( χ (3) ) at a Fe concentration of about 15% were 6.73 × 10 −7 esu and −1.02 × 10 −7 esu, respectively.