Self-phase modulation and ring pattern observation by applying electrical field on dye-doped nematic liquid crystal

In this work, we report the experimental results of two typical liquid crystals (6CHBT and w1680) in the nematic phase while they have been doped with Sudan dyes compared with pure state. We investigate the AC-applied voltage effect on the nonlinear behavior of dye doped liquid crystal (DDLC). The novel effects on the far-field diffraction patterns of a Gaussian beam depend on the external applied field. The measurements were performed using CW He:Ne laser and Nd:Yag laser at 632.8 nm and 532 nm, respectively. The z-scan technique is used to measure the amplitude and the sign of the nonlinear refractive indices DDLC. The nonlinear refractive indices were in order of 10− 5 cm2/W. Also the nonlinear absorption coefficient β was measured using open aperture z-scan technique.