Thermal properties of a new dye compound measured by thermal lens effect and Z-scan technique

Abstract

A new dye compound containing azomethine groups has been synthesized and characterized by FT-IR, ¹³C NMR, and an UV–visible spectrometer. Measurements of the thermally induced optical nonlinearity of dichloro bis[2-(2-hydroxybenzylideneamino)-5-methylphenyl] telluride platinum(II) in a chloroform solvent were studied using a cw diode laser at 487 nm as the source of excitation, both in solution and as a poly methyl methacrylate solid film, respectively. The optical response was characterized by measuring the intensity-dependent refractive index n ₂ of the medium using the Z-scan technique. The sample showed negative and large nonlinear refractive index values of the order of 10⁻⁷ cm²/W and reverse saturable absorption with high values of the nonlinear absorption coefficient of the order of 10⁻³ cm/W. The nonlinear refractive index was found to vary with the concentration. These results indicate that the dye is a promising candidate for applications in the nonlinear optic field. Thermal lens spectrometry was applied to investigate the thermo-optical properties and the nonlinear refractive index. In this technique, a pump and a probe beam were aligned collinearly. A localized change in the refractive index of the sample due to the thermal heating produced a thermal lens, which was then detected by studying the focusing and defocusing of the pump and probe beam.