Third-order optical non-linearities of excited states in diphenyl-polyene derivatives: A sub-picosecond study

The third order optical non-linearities chi((3)) of some excited diphenyl-polyene derivatives (t-stilbene, 1,4 diphenyl-butadiene, 1,6 diphenyl-hexatriene, 1,8 diphenyl-octatetraene) have been studied using Degenerate 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 taking into account the symmetry of excited states and resonance conditions. The dynamics of chi((3)) has been measured and may show fast or slow regimes, depending on the compound. The spectral dependence of the real and imaginary part of the optical non-linearity have been measured.