Third-order optical nonlinearities in methoxy-substituted 1,3 diphenyl propenones by Z-scan and Optical Limiting studies

Employing the single beam Z-scan technique with nanosecond laser pulses at 532nm, the refractive and absorptive nonlinearities of methoxy-substituted (2E)-1-(3,4-dimethoxyphenyl)-3-phenylprop-2-en-1-one have been studied. The methoxy substitution makes 3,4-dimethoxy chalcone derivatives a donor-acceptor-donor (D-A-D) type intramolecular charge transfer molecule. The sign of the nonlinear index of refraction (n 2 ) is found to be negative and the magnitude n 2 is of the order of 10 -11 esu. The variation of NLA coefficient (β eff ) with input intensity (I 0 ) is studied and the nonlinear absorption mechanism is found to be sequential two-photon absorption(TPA) leading to thermal effects in the solutions. The enhancement of nonlinearity due to the methoxy substitution is in accordance with the dipole-like formation in the said molecules. The compounds exhibit good optical limiting as well.