Heterodyned Femtosecond Optical Kerr Effect of Substituted Conjugated Polymers

The femtosecond optical heterodyne detected optical Kerr effect is described.The real and the imaginary parts of complex third-order optical nonlinearity can be effectively separated and their values and signs can be determined.Using this method,we have thoroughly investigated the substitution effect by adding side-groups on the-(-C=N-)-conjugated system,a new class of nonlinear optical material,and find that the polybenzonitrile(γr=-1.59 x10^(-31) esu,m=6)is an order of magnitude superior to poly-amino-nitrile.But when we further add substituents on benzoid rings,the enhancement is limited.We can say that for the series of polybenzonitrile,the benzoid ring can improve the x^(3)value more effectively than other substitutions.