Engineering Physics Annotation << Back About Mechanism Propagation Light Flux in Optical Waveguides Egorov V.K., Egorov E.V. The paper briefly formulates the generally accepted paradigm of light propagation in optical fibers based on the phenomenon of total internal refl ection at interfaces separating materials with different refractive indices of optical radiation. The features of the phenomenon of total internal refl ection are described and the fact of ignoring, within the framework of the generally accepted approach, the formation of interference fi elds, which are the results of interaction between the incident and refl ected optical fl ux is pointed out. In addition, it is pointed out that the generally accepted paradigm does not take into account the factor of the degree of monochromaticity of optical radiation, which in addition to the parameter λ0 is characterized by the presence of the value ∆λ and the parameter of coherence length. It is shown that taking these factors into account allows us to assert that fl uxes of quasi-monochromatic optical radiation can propagate under the conditions of their transport by a symmetric optical waveguide either in accordance with the mechanism of multiple total internal refl ections or its waveguide-resonance propagation. A model of the mechanism of which is also presented in the paper. Based on the comparison of the features of these mechanisms, it is concluded that optical fibers function by the mechanism of waveguide-resonance propagation of light fl uxes. Keywords: Fiber, waveguide-resonance propagation, total internal reflection, interference, standing wave. DOI: 10.25791/infizik.8.2025.1496 Pp. 15-31.