Prominent Second-Order Nonlinear Optical Properties of Novel Ketone Derivatives

We have studied the substituent effect of bis(benzylidene)-cycloalkanones (BBCAs) on the second-order nonlinear properties. As the result of strong donor introduction, the effective second-harmonic generation (SHG) coefficient of 2,6-bis(4′-dimethylamino-benzylidene)cyclohexanone (DMABCH) was found to be 5.3 times as large as that of m-nitroaniline at 1.06 μm. The cutoff wavelength is determined to be 530 nm. The space group symmetry of DMABCH is observed to be mm2, as is the case for BBCAs without strong donor. As for chiral effect, the SHG coefficients of chiral BBCAs are as large as that of m-nitroaniline.