Unidirectional guided resonances in anisotropic waveguides

We show that anisotropic planar anti-guiding waveguide structures with two radiation channels toward the surrounding cladding materials can support unidirectional guided resonances (UGRs), where is canceled in one of and redirected into other. Their formation subtle as it requires breaking so-called polar anisotropy-symmetry structures. Then, UGRs appear at specific wavelengths light propagation directions, are robust, characterized by phase singularities channel which canceled. The mechanism we describe allows for ready selection direction, well tuning wavelength angle occur.