Synthesis and Characterization of ZnS/Ag2S Nanocomposites with Enhanced Kerr-Type Optical Nonlinearity

Abstract

Fabrication and performance of ZnS/Ag2S nanocomposites as an optical material for efficient Kerr nonlinearities have been described in this study. The formation and composition of samples were verified using combined techniques such as XRD, FTIR, FESEM, EDS and HRTEM. Spectrophotometer methodologies including UV–Vis DRS and PL spectroscopy were employed to analyze the linear optical characteristics. A red shift towards visible light absorption wavelengths was detected in the band-gap energy of ZnS/Ag2S nanocomposites as compared to the sole ZnS sample. The coupling process between ZnS and Ag2S confirmed a promoted charge-carrier separation at the interface of composite structures, supported by PL results. The nonlinear optical studies were performed using standard single-beam Z-scan technique under a 1064 nm Nd-YVO4 laser with 50 ns pulse width and 10 kHz repetition rate as an excitation source. The composite structure effect resulted in an enhanced Kerr-type optical susceptibility of about 52.9 × 10–6 esu, which was eight orders of magnitude higher than that of ZnS structures (7.1 × 10–6 esu).