Facile hydrothermal synthesis of CdFe2O4-reduced graphene oxide nanocomposites and their third-order nonlinear optical properties under CW excitation

Third-order nonlinear optical response of cadmium ferrite loaded upon various content of reduced graphene oxide was studied by single beam Z-scan technique using Nd: YAG laser (532 nm, 50 mW). In XRD disappearance of characteristic peak of graphene oxide (10.7°, (100)) and appearance of peaks of reduced graphene oxide (23.3°, (002)) along with cadmium ferrite (34.2°, (311)) confirms the trimming of CdFe2O4 upon rGO. Further the successful trimming of rGO with CdFe2O4 was further evidenced by FTIR and high-resolution C 1s XPS. FESEM and TEM image of GO show folded sheets of graphene layers due to strong oxidation and reduction process. And pure CdFe2O4 grow themselves as nanorods which upon trimming on the surface of graphene sheets suffered a morphological change with respect to the content of graphene oxide (rods to platelets). Absorption spectra of decorated composites possess, absorption peaks at 230 nm (π-π* transition in aromatic CC), 292 nm (n-π* transition in CO bonds) and 425 nm (cadmium ferrite). Z-scan results showed that both pure and decorated samples showed saturable absorption and self-defocusing behavior along with optical limiting action. Also the nonlinear refraction was found to be more dominant than nonlinear absorption due to strong contribution arising from thermal components. Upon trimming, the nonlinear refractive index (10−8 cm2/W), nonlinear absorption coefficient (10−3 cm/W) and third-order nonlinear optical susceptibility (10−6 esu) were found to be increasing with increase in graphene content. Variation in the distribution and morphology of CdFe2O4 has resulted in the tunability of third-order NLO coefficients and limiting threshold (9.3-30.4 mW). Nanoplatelet CdFe2O4-40 wt% rGO displays good optical power handling capability of laser beam at the experimental wavelength, indicating the possible photonics device application such as optical power limiters.