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Large-Angle, Broadband and Multifunctional Directive Waveguide Scatterer Gratings
摘要： Conventional surface-relief gratings are inefficient at deflecting normally-incident light by large angles. This limits the overall efficiency of grating-based optical instruments and also restricts their use in many applications. Here, we demonstrate a simple approach for the design of diffraction gratings that can be highly efficient for large deflection angles, while also offering additional functionality. Such gratings are composed of a unit cell comprising a vertically-oriented asymmetric slot waveguide. The unit cell shows oscillating unidirectional scattering behavior that can be precisely tuned as a function of the waveguide length. This occurs due to interference between multiple modes excited in the structure by the incident light. In contrast to metasurface-based gratings with multiple resonant sub-elements, a periodic arrangement of such non-resonant diffracting elements allows for broadband operation and a strong tolerance for variations in angle of incidence. Full-wave simulations show that our grating designs can exhibit diffraction efficiencies ranging from 94% for a deflection angle of 47? to 80% for deflection angle of 80?. To demonstrate the multifunctionality of our approach, we also demonstrate a flat polarization beamsplitter and a polarization insensitive grating.
关键词： directional scattering,slot waveguides,diffraction gratings,metagratings,bianisotropy
更新于2025-09-12 10:27:22
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Simulation of Circular Cylindrical Metasurfaces using GSTC-MoM
摘要： Modeling of circular cylindrical metasurfaces using Method of Moments (MoM) based on Generalized Sheet Transition Conditions (GSTCs) is presented. GSTCs are used to link the integral equations for fields on the inner and outer contour of the circular cylindrical metasurface. The GSTC-MoM is validated by two examples: (1) anisotropic, gyrotropic metasurface capable of two field transformations, (2) non-gyrotropic metasurface capable of transforming field generated by an infinite electric line source at origin to field generated by a displaced electric line source. The formulations presented here can be used as a platform for deriving GSTC-MoM for 3D spherical and conformal metasurfaces.
关键词： GSTC,Integral Equation,Metasurface,MoM,Electromagnetic discontinuity,Boundary condition,Susceptibility,Bianisotropy,Cylindrical
更新于2025-09-10 09:29:36