Phase modulation and optical anisotropy of high birefringence liquid crystal mixtures are studied in this work. Phase measurements are performed via voltage dependent interferometric pattern shifts at a wavelength of 632.8 nm. Wavelength dependence of optical anisotropy is carried out by polarizing microscopy via transmittance spectra from 450 nm to 720 nm. Nematic liquids crystal mixtures are sandwiched between two glasses which are homogeneously aligned and assembled untwisted. The results of phase shifts are compared to those of conventional nematic liquid crystals. It has been shown that high birefringence liquid crystals are potential candidates for generating phase shifts which are higher (similar to 6 pi) than those of conventional nematic liquid crystals (normally about 2 pi).