Self-defocusing, Kerr nonlinearity of green light emitting phosphors, Calcium–Strontium bimetallic tungstate nanoparticles decorated rGO

Abstract Hydrothermal method has been employed to prepare bimetallic tungstate CaSrWO4- rGO as a 3D/2D nanocomposite with various concentrations such as 0.5, 1 and 5 wt. %. The primary concern of this work is to carryout structural characterization of the synthesized nanocomposite and to investigate its third-order optical nonlinearities. The growth of CaSrWO4 on the surface of rGO sheets with uniform particle size distribution is evident from SEM and is augmented by TEM analysis. The formation of CaSrWO4/rGO nanocomposite is confirmed with the appearance of the D and G band with an increase in the ID/IG ratio as observed in the Raman spectra and with the shift of Ca 2p and Sr 2p singlet towards higher binding energy in the XPS spectra. The linear optical properties exhibit a broad absorption in the UV vis spectra and the drastic fall in the electron-hole recombination rate after the addition of rGO in the composite is signified by the transitions of e-s between the intermediate energy levelsexplicited in the PL spectra. For the first time, CaSrWO4/rGO nanocomposite has been investigated for third-order optical nonlinearities by using the Z-scan method in which the nanocomposite is being irradiated with a Gaussian beam of continuous wave of 532 nm wavelength. Nonlinear absorption of CaSrWO4/rGO nanocomposite exhibits a higher reverse saturable absorption and the two-photon absorption β is calculated to be around 7.2 ⨯ 10−5 (cm/W). CaSrWO4/rGO nanocomposite exhibits a self-defocusing effect in nonlinear regime prioritizing it to be a potential optical limiter.