Ultrafast and short pulse optical nonlinearities of meso-tetrakis-(2,3,5,6-tetrafluoro-N,N,N-trimethyl-4-aniliniumyl) porphyrin and its metal complexes

• We examined the third order NLO properties of a series of metallo porphyrins by Z scan (ns and fs) and DFWM (ns).
• The χ(3) values are found to be increasing with the d-shell occupancy of central metal atoms.
• Electrostatic potential (ESP) mapping is done to establish the structure property relationship.
• The results obtained are in accordance with the ESP plots.
• It is found that the heavy metal atom effect plays a crucial role in enhancing the nlo response of metalloporphyrins.

Among the various classes of Nonlinear Optical chromophores, porphyrins appear to have exclusive characteristics that make them superior to other compounds as optical materials. Here we report the experimental analysis on the nonlinear optical properties of a new series of porphyrins, meso-tetrakis(2,3,5,6-tetrafluoro-N,N,N-trimethyl-4-aniliniumyl) porphyrin and its central metal substitutions using Z-scan technique under nanosecond (532 nm, 7 ns) and femtosecond (800 nm, 100 fs) excitations. The compounds were found to exhibit two photon absorption assisted excited state absorption in the nanosecond regime and effective three photon absorption in the femtosecond regime. The third-order nonlinear optical susceptibilities (χ(3)) were of the order 10−11 esu and are compared through degenerate four wave mixing (DFWM). The compounds showed good optical limiting behavior in both femtosecond and nanosecond regimes which find applications in laser safety. The structure property relationship has been established with the support of Electrostatic Surface Potential (ESP) mapping.

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