Nonlinear optical performance of chemically tailored phthalocyanine-polymer films as solid-state optical limiting devices

Linear and nonlinear optical (NLO) investigations into the material response of a selection of solid-state phthalocyanine-polymer films are reported. Using the simple method of sequentially deposited spin cast phthalocyanine doped polymer films, one can characterize the resulting NLO response by means of the Z-scan technique with 6 ns pulses at 532 nm. Effective optical coefficients are calculated with a nonlinear absorption based model and their intensity dependence is investigated. When compared with the phthalocyanine solutions, the phthalocyanine-poly(methyl methacrylate) (PMMA) films exhibit excellent nonlinear extinction effects, outperforming corresponding phthalocyanine solutions by 2-3 orders of magnitude. Molecular engineering of metallophthalocyanine compounds, through both axial and peripheral substitutes, has led to an optimization of the resulting NLO response in the nanosecond regime. Mechanistic implications of the optical dissipation for various substituted phthalocyanines are also discussed and examined.