Enhancement of nonlinear optical response and fluorescence spectra of cationic neutral red by anionic surfactant

Abstract

Two-photon absorption (TPA) and fluorescence intensity have possibilities for application in photodynamic therapy and photonic devices. The nonlinear optical properties of the cationic neutral red dye (NR) encapsulated in nanodroplets were studied using the Z-scan technique. The nanodroplets were prepared with a mixture of water, oils, and anionic Bis (2-ethylhexyl) sulfosuccinate sodium salt (AOT). The TPA and nonlinear refractive (NLR) index were studied in three different systems; NR in nanodroplets, NR in AOT and water, and NR in a different solvent. The results indicated that the TPA and NLR index spectra of NR depend on the droplet size. The TPA of the NR dye in the nanodroplet is enhanced in comparison to the NR/solvent system. Moreover, the second-order hyperpolarizability and fluorescence activity of the NR are affected by the encapsulation in the nanodroplets.