Effect of Photo-Isomerization of Azo Dyes on the Photonic Bandgap in Chiral Nematics

David Statman; Andrew Jockers; Daniel Brennan

doi:10.4028/www.scientific.net/SSP.181-182.257

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Effect of Photo-Isomerization of Azo Dyes on the Photonic Bandgap in Chiral Nematics
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HomeSolid State PhenomenaSolid State Phenomena Vols. 181-182Effect of Photo-Isomerization of Azo Dyes on the...

Effect of Photo-Isomerization of Azo Dyes on the Photonic Bandgap in Chiral Nematics

Abstract:

Chiral nematic liquid crystals prepared with Grandjean texture demonstrate a photonic bandgap whose central wavelength is proportional to the pitch length, P, of the liquid crystal and whose width is given by (n_e – n_o)P. We show that methyl red doped chiral nematics undergo a shift in the photonic bandgap upon photo-isomerization. This shift is a result of (1) photo-induced change in anchoring energy on the nematic surface, and (2) change in the natural pitch length from the photo-isomerization of the azo dye.