Antiresonant reflecting optical waveguide microstructured fibers revisited: a new analysis based on leaky mode coupling.

Using two different modal methods, the multipole method and the more recent fast Fourier factorization method, we exhibit and explain a core mode transition induced by avoided crossing between a core localized leaky mode and an high-index cylinder leaky mode in anti-resonant reflecting optical waveguide microstructured optical fibers (ARROW MOFs). Due to its wavelength selectivity and to the leaky nature of the involved modes, this transition doesn't seem to have already been described in detail and analyzed as done in this work in spite of several already published studies on core mode dispersion properties. The main properties of this transition are also described. We also revisite the already mentionned cut-off phenomena limiting the transmission band in ARROW MOFs in terms of mode coupling between the core mode and one or several high- index cylinder modes.