Intuitive Equivalence Between Radiation Modes and Quasi-Leaky Modes in Optical Waveguides

Field distributions and power spectra of radiation modes in both two-layer and three-layer cross-sectional fibers are investigated. By mapping packets of radiation modes to discrete complex modes, the relationship between the radiation modes and the quasi-leaky modes obtained in an equivalent numerical model is revealed. Simulation results further show that quasi-leaky modes can accurately and intuitively describe packets of radiation modes, from the viewpoint of power distribution and attenuation in the mode propagating. The normalization and orthogonality of quasi-leaky modes as well as the model parameters of the equivalent numerical model are discussed.