The index of refraction for left circularly polarized (LCP) and right circularly polarized (RCP) light is the same as for linearly polarized light in isotropic materials. However, in anisotropic materials, the polarization of light influences the apparent index of refraction due to varying permittivities and permeabilities based on the orientation of the incident fields. Birefringent materials demonstrate that circularly polarized light can be viewed as a combination of two linearly polarized waves, leading to different behaviors compared to linear polarization. In chiral media, including isotropic substances like sugar solutions, the index of refraction differs for LCP and RCP waves, a phenomenon known as circular birefringence. Consequently, the index of refraction is not clearly defined for linearly polarized waves in such media, as they are combinations of LCP and RCP components.