Third order nonlinear optical properties and optical limiting in donor/acceptor substituted 4/-methoxy chalcone derivatives

The third order nonlinear optical properties of 4'-methoxy chalcone and its derivatives have been investigated using a single-beam Z-scan technique with nanosecond laser pulses at 532 nm. The 4'-methoxy chalcone and its derivatives are donor--acceptor--acceptor (D--A--A) and donor--acceptor--donor (D--A--D) type intramolecular charge transfer molecules. The nonlinear response in these molecules was found to increase with increase in (a) the electron acceptor strength in D--A--A type and (b) the donor strength of the substituted group in D--A--D type molecules. The Delta *y(3) value in these molecules is found to be of the order of 10-13 esu. The observed increase in the third order nonlinearity in these molecules clearly indicates the electronic origin. The compounds exhibit good optical limiting at 532 nm. The best optical limiting behavior was observed with the molecule substituted by a strong electron donor.