Laser-induced nonlocal refractive index change in methyl red-doped nematic liquid crystal E7

Abstract

Laser-induced index change in a dye-doped nematic liquid crystal is observed under crossed polarizers using the pump-probe technique. A pump beam (Argon-ion laser, λ = 514.5 nm) incident on a 32-μm thick homeotropic sample of methyl red-doped nematic E7 induces a reorientation of the director that changes the sample index, observed as a change in the probe beam transmittance (He-Ne laser, λ = 632.8 nm). A two-dimensional profile of the transmittance shows the index change is present even in areas outside the pump beam illumination. A schematic profile of the director reorientation is presented to explain the observed effect.