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arXiv · 1807.01888

Bound states in the continuum and high-Q resonances supported by a dielectric ridge on a slab waveguide

Evgeni A. Bezus·Dmitry A. Bykov·Leonid L. Doskolovich
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Abstract

We investigate the diffraction of guided modes of a dielectric slab waveguide on a simple integrated structure consisting of a single dielectric ridge on the surface of the waveguide. Numerical simulations based on aperiodic rigorous coupled-wave analysis demonstrate the existence of sharp resonant features and bound states in the continuum (BICs) in the reflectance and the transmittance spectra occurring at oblique incidence of a TE-polarized guided mode on the ridge. Using the effective index method, we explain the resonances by the excitation of the cross-polarized modes of the ridge. The formation of the BICs is confirmed using a theoretical model based on the coupled-wave theory. The model suggests that the BICs occur due to coupling of quasi-TE and quasi-TM modes of the structure. Simple analytical expressions for the angle of incidence and the ridge width predicting the location of the BICs are obtained. The existence of high-Q resonances and BICs makes the considered integrated structure promising for filtering, sensing, transformation of optical signals, and enhancing nonlinear light-matter interactions.

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Evgeni A. Bezus, Dmitry A. Bykov, Leonid L. Doskolovich. 2018-07-05. Bound states in the continuum and high-Q resonances supported by a dielectric ridge on a slab waveguide. https://doi.org/10.1364/prj.6.001084

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