Leaky waves, wood´s anomalies and extraordinary optical trapping

We discuss the possibility of trapping light within the continuum of radiation modes, realizing resonant states with diverging Q factor, based on the anomalous interaction of diffracted waves and leaky guided modes in diffraction gratings. These trapped optical states can be predicted within the framework of well-established leaky-wave theory. Our approach may also provide important physical insight on similar embedded eigenstates recently demonstrated in the literature.