Abstract. The paper presents the principle of the operation of a spectropolarimetric interferometer. In a planar waveguide orthogonal modes of the TE and TM types can be excited for the entire visible light. During the propagation the difference of the phases between the modes was determined, which is the function of the length of the path of propagation, the difference of the effective refractive index (NTM-NTE) and the wavelength. At the output of this system the spectral distribution of intensity was recorded, the shape of which depends on the value of the refractive index of the cover of the waveguides.