Femtosecond optical Kerr study of heavy atom effects on the third-order optical nonlinearity of thiophene homologues: purely electronic contribution

A novel selenoalkenyl-isoxazole based donor-acceptor nonlinear optical material

The structure property relationships of untwinned enantiomorphic Z-(methylseleno)alkenyl-substituted phenyl-isoxazole and its isostructural triazole congener both crystallizing in the P2₁2₁2₁ space group were investigated with respect to UV/vis absorption, thermal behaviour, and second harmonic generation ability. Differential scanning calorimetry revealed a significantly higher melting point of the novel isoxazole compound compared to the triazole derivative and therefore a broader thermal application window. The SHG efficiency of the isoxazole derivative is approximately two thirds the value of the triazole compound and approximately 27 times higher than potassium dihydrogen phosphate. Thus, the developed molecular scaffold represents an interesting novel type of nonlinear optical (NLO) chromophore.

Wavelength dependence and figures of merit of ultrafast third-order optical nonlinearity of a conjugated 3,3'-bipyridine derivative

The wavelength dependence and figures of merit of the third-order optical nonlinearity of a conjugated 3,3'-bipyridine derivative, a designed nondipolar structure of the donor-acceptor-acceptor-donor type, are reported. Z scans reveal positive nonlinear refractive-index changes for wavelengths longer than the one-photon absorption wavelength. Although the value of nonlinear Kerr coefficient n2 decreases from 6.0(+/- 0.2) x 10(-6) cm2/GW at 750 nm to 4.6(+/- 0.7) x 10(-6) cm2/GW at 1550 nm, the value of nonlinear absorption beta decreases from 0.084 cm/GW at 750 nm to a negligible value at 1550 nm, giving rise to excellent nonlinearity-to-loss figures of merit at telecommunications wavelengths.