The design and fabrication of active and passive hybrid photonic devices, with tunable optical properties, based on liquid crystals require a very accurate knowledge of their anisotropic refractive indices up to 100ppm in the wavelength region of interest. At this aim, the authors have integrated two standard optical techniques commonly used in liquid crystals characterization, the variable angle spectroscopic ellipsometry and the half leaky guided mode spectroscopy, exploiting their best performances and overcoming their limits. The dispersion curves of nematic liquid crystal E7 have been estimated in the 450–1700nm wavelength interval with both precision and accuracy of 10−4.