INVESTIGATION OF THIRD-ORDER NONLINEAR OPTICAL PROPERTIES OF BFDT-DOPED PMMA THIN FILMS USING Z-SCAN TECHNIQUE

摘要

A series of polymeric thinlms with BFDT (BFDT = 4,5-bis(foroylsulfanyl)-1,3-dithiole-2-thione) doped in PMMA (polymethylmethacrylate) were fabricated by means of spin-coating on quartz substrate. The third-order nonlinear optical properties of thelms were investigated by Z-scan technique at 532 nm wavelength with 20 ps pulse width. The in uences of doping concentration for third-order nonlinearity were also studied. A self-defocusing eect was observed from the Z-scan curves and the nonlinear refractive index of the lm increases with the increase in doping concentration. Our results suggest that considerable nonlinear optical properties were found in BFDT. In addition, it was found that the nonlinear coecient of the BFDT-doped PMMA thin lm was about two orders of magnitude larger than that of homologous materials with organic solvents. By analysis, we can conclude that the material is a potential candidate for applications of nonlinear optics and can be considered in the fabrication of all-optical switching devices,etc.