2-PHOTON ABSORPTION AND BROAD-BAND OPTICAL LIMITING WITH BIS-DONOR STILBENES

Large two-photon absorptivities are reported for symmetrical bis-donor stilbene derivatives with dialkylamino or diphenylamino groups. These molecules exhibit strong optical limiting of nanosecond pulses over a broad spectral range in the visible. Relative to bis(di-n-butylamino) stilbene, bis(diphenylamino)stilbene exhibits a 90-nm red shift of its optical limiting band but only a minimal shift of similar to 13 nm of its lowest one-photon electronic absorption band. Mixtures of these c ompounds offer an unprecedented combination of broad optical limiting bandwidth and high linear transparency. (C) 1997 Optical Society of Am erica.