Dendrimer molecules with record large two-photon absorption cross section

We report what is to our knowledge a record high value for an intrinsic two -photon absorption (TPA) cross section, sigma (2) = 11 x 10(-47) cm(4) s ph oton(-1) molecule(-1), measured with femtosecond pulses in a new dendrimer molecule comprising 29 repeat units of 4,4 ' -bis(diphenylamino)stilbene ch romophore. We measure the dependence of TPA on excitation wavelength in thr ee consecutive generations of the dendrimer and show that the maximum sigma (2) value increases faster than the total number of stilbene chromophores. This result indicates that it is possible to obtain even larger sigma (2) values in higher generations of this dendrimer family. (C) 2001 Optical Soc iety of America.