Nonlinear optical extinction in organic and inorganic nanomaterials

Abstract

This thesis will focus on the nonlinear optical dissipation of high intensity nanosecond laser irradiation by polymer-phthalocyanine films and nano-structured dispersions. The nonlinear optical investigation of a selection of solid-state polymer-phthalocyanine films is initially presented. Using the straightforward method of sequentially deposited spin cast phthalocyanine doped polymer films, the resulting nonlinear optical response was characterized by the use of the open aperture Z-scan technique. Molecular engineering of metallophthalocyanine compounds, through both axial and peripheral substitutes has led to an optimisation the nonlinear optical response of the compound in the nanosecond regime. Effective optical coefficients with a nonlinear absorption based model are calculated, and their intensity dependence is investigated. Mechanistic implications of the optical dissipation are also discussed and examined in three separate case studies. For the optical limiting experiments the open aperture Z-scan technique was used probing total transmittance through the sample. The second harmonic, 532nm, of a Qswitched Nd:YAG laser was used with a pulse repetition rate of 10Hz. The beam was spatially filtered to remove the higher order modes and tightly focused with a 9cm focal length lens.