Institution: | aPhotonics Laboratory, Physics Department, Tarbiat Moallem University, Mofateh 49, Tehran, Iran bMedical University of Qom, Qom, Iran |
Abstract: | Recently the nonlinear effects of the azo-dye doped liquid crystals have attracted much interest. In this paper the nonlinear refractive indices, n2, of two dyes (Sudan Black B, Sudan III) doped nematic liquid crystal were measured at low laser powers using moiré deflectometry technique. The results show when a nonlinear sample is placed in moiré deflectometry setup, the moiré fringe patterns will rotate around the beam center because of self-focusing effect in the sample. By measuring this rotation, the magnitude and the sign of nonlinear refractive index were calculated. The n2 values for Sudan black B is larger than Sudan III, because of some differences in molecular structure and molecular polarization. |