Measurement of nonlinearity and spectral study of a laser dye

Problem statement: The third order nonlinear optical properties of organic Polymers are used in high speed telecommunications, optical limiters and optical; computes. The purpose of study was to determine the spectral and third order nonlinear characteristics of the organic dye, Victoria blue in liquid and in solid medium. Approach: The samples were prepared by dissolving the dye in n-butyl acetate (liquid medium) and a thin film of thickness 1mm was prepared by bulk polymerization method. The spectral characteristics of victoria blue dye doped poly (methyl methacrylate) modified with additive n-butyl acetate (nBA) are studied by recording its absorption and fluorescence spectra and the results are compared with the corresponding liquid mixture. The nonlinear refractive index of the dye in nBA and dye doped polymer film were measured using z-scan technique [1], by exciting with He- Ne laser. The results obtained are intercompared. Results: Both the samples of dye Victoria blue in liquid and solid medium show a negative nonlinear refractive index. A negative nonlinear dye doped films can be used as optical limiters. The origin of optical nonlinearity in the dye may be attributed due to laser-heating induced nonlinear effect. PACS Code: 42.55.Mv, 42.65.-k, 82.35.Ej, 42.70.Jk