Guiding light through quasi-TE modes embedded in the radiation continuum

Abstract: We introduce a new type of a bound state in the continuum (BIC) which appears in the photonic structure consisting of two coupled waveguides where one of them supports a discrete eigenmode spectrum embedded in the continuum of the other one. A BIC appears when the coupling is suppressed by suitable tuning of structural parameters. In contrast to the previously described configurations, our scheme facilitates genuine guiding of quasi-TE modes in the core with the lower refractive index.