Linear and nonlinear optical properties of rhodamine B, methylene blue, and saffron dyes in the presence of silver nanoparticles (Ag NPs)

In this study, we investigated the optical properties of the rhodamine B, methylene blue, and saffron dyes in the presented silver nanoparticles (Ag NPs). We detected that the absorption of the rhodamine B and methylene blue increased by interacting with NPs due to plasmon-induced quenching this effected can be utilized to manipulate and enhance optical properties and as a laser active medium. The highest value of the absorption coefficient for pure rhodium tincture was 222.86 cm-1, and for saffron dye tinged with silver nanoparticles was 486.98 cm-1. We studied the nonlinear optical responses of silver nanoparticles and these dyes. We detected that the silver nanoparticles have a high linear response at all selected laser excitations. In additionally, rhodamine B has a higher nonlinear response at a wavelength of 450 nm, which was further enhanced by the silver nanoparticles. Methylene blue has nonlinear responses, especially at the maximum absorption wavelength of 650 nm, and saffron dye showed nonlinear responses at all wavelengths, but the best response was at the 405 nm laser. The nanoparticles enhanced the nonlinear refraction of the saffron dye to fit the absorption spectra. The highest value of the nonlinear refractive index for saffron dye a doped with silver nanoparticles at a 405 nm laser was 3.48 × 10-11. These results indicate that the addition of nanoparticles can enhance the nonlinear properties of these dyes with the use of dye-appropriate lasers in Z-Scan technology.