MAGNETO-OPTIC EFFECTS IN NEMATIC LIQUID CRYSTAL DOPED WITH AZO-DYES

Nematic liquid crystal cells were subjected to different DC magnetic fields and the optical transmission of a He-Ne laser beam was recorded for different field values. It was found that a small addition of Methyl Orange (MO) induced optical activity into the nematic sample. When the cells were subjected to increasing magnetic field, the rotatory power (rotation angle) varied periodically; the same occurred for the light transmission and ellipticity. We found that the light emerging from the liquid crystal cell is elliptically polarized and in some cases circularly polarized. After UV light irradiation (365 nm) the rotatory power of the sample increases. The position of rotation angle maxima and minima is slightly affected by the irradiation.