Photochemical Control of Phase Structure of Liquid Crystals with a Two-Photon Absorbing Stilbene Dye

Abstract

Photochemical phase transition behavior of nematic liquid crystals (LCs) induced by two-photon excitation of a photosensitive dye was studied. Bis-donor substituted stilbene was synthesized as a two-photon absorbing (TPA) chromophore, and its one-photon and two-photon induced isomerization behavior was investigated in a solution and in a LC matrix. Irradiation of a stilbene/host LC mixture with pico-second laser pulse at 680 nm (20 ps, fwhm) induced the change in the phase structure of the LC. Since the stilbene dye show no one-photon absorption at this wavelength, the observed change in the LC phase structure results from the trans-cis isomerization of stilbene induced by two-photon excitation.