3D15 液晶フォトニクス材料 : ドナー・アクセプターを有するアゾベンゼン液晶の光異性化を利用した高速光スイッチング

概要

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Optical switching has been explored by the use of liquid-crystalline(LC) material with photosensitive moleties. Polymeric push-pull type azobenzene was prepared, which shows nematic(N) LC behavior in the trans form while no LC phase in the cis isomer. Photoirradiation at 366 nm of very thin film (〜100 nm) of the liquid-crystalline azobenzene derivative in the trans form resulted in disappearance of the N phase due to trans-cis photoisomerization of each mesogen, and the N phase recovered rapidly when the irradiated sample was kept at high temperature in the dark because of cis-trans thermal isomerization and reorientation of the mesogenic trans-azobenzenes. Time-resolved measurement by the use of a laser pulse (355 nm; 10 ns FWHM) revealed that N to isotropic (I) phase transition took place in 200 μs. The N-I phase transition was also induced in 200 μs even at room temperature. The thermal I-N phase transition occurred in 1 s at 135 ℃. In addition, irradiation of visible light (>420 nm) after irradiation of the pumping light accelerated the I-N phase transition.
日本液晶学会の論文
1995-09-10