Donor/acceptor effects on the nonlinear optical properties of 1,3 diphenyl propenones

Abstract

Employing the single beam Z-scan technique with nanosecond laser pulses at 532 nm, the refractive and absorptive nonlinearities of donor and acceptor substituted (2E)-1-(3,4-dimethoxyphenyl)-3-phenylprop-2-en-1-one have been studied. The sign of the nonlinear index of refraction (n ₂) is found to be negative and the magnitude of n ₂ is in the order of 10⁻¹¹ esu. The second-order molecular hyperpolarizability (γ_h) is calculated to be in the order of 10⁻³² esu. The variation of nonlinear absorption coefficient (β_eff) with input intensity (I ₀) is studied and the nonlinear absorption mechanism is found to be reverse saturable absorption (RSA). The enhancement of nonlinearity due to the donor and acceptor substitution is in accordance with the variation in π electron delocalization in the molecules. The compounds exhibit good optical limiting as well.

Keywords:

• Z-scan
• two-photon absorption
• optical limiting
• nonlinear refractive index

Acknowledgements

The authors wish to thank Dr John Kiran, Ajou University, Suwon, South Korea, for his many useful discussions. They also thank Ravindra H.J., Mangalore University, India, for his help in preparing the samples.