3RD-ORDER OPTICAL NONLINEARITIES OF EXCITED-STATES IN DIPHENYL-POLYENE DERIVATIVES - A SUBPICOSECOND STUDY

The third order optical non-linearities chi((3)) of some excited diphe nyl-polyene derivatives (t-stilbene, 1,4 diphenyl-butadiene, 1,6 diphe nyl-hexatriene, 1,8 diphenyl-octatetraene) have been studied using Deg enerate Four Wave Mixing (DFWM) and Optical Kerr Effect (OKE) on a sub -picosecond time-scale. Strong enhancements of chi((3)) between ground and excited states are observed for some compounds and discussed taki ng into account the symmetry of excited states and resonance condition s. The dynamics of chi((3)) has been measured and may show fast or slo w regimes, depending on the compound. The spectral dependence of the r eal and imaginary part of the optical non-linearity have been measured .