Third-order nonlinear optical properties and two-photon absorption in branched oligothienylenevinylenes

We report measurements of the third-order susceptibilities and two-photon absorption in branched oligothienylenevinylenes derivatives C42H62S2, C114H174S6, C252H366N3O6P3S12, using degenerate four wave mixing (DFWM) technique at lambda = 532 nm in picosecond regime. All the studied compounds show large third-order nonlinear optical properties with comparison with known materials such as, polydiacetylene, octupolar molecules and their dipolar subunits. We show the influence of the number of branches on the benzene cycle. We demonstrate that the values of third-order susceptibilities lambda((3)) and two-photon absorption coefficients beta increase as the number of branches increase. As consequence the studied complexes can be very interesting for optical limiting applications. (C) 2002 Elsevier Science B.V. All rights reserved.