Waveguide Coupling via Magnetic Gratings with Effective Strips

Applied Sciences

Augustine M. Urbas¹  Vladimir P. Drachev²  Kevin M. Roccapriore²  David P. Lyvers²  Thomas A. Germer³  Ekaterina Poutrina⁴  Dean P. Brown⁴ 

[1] Air Force Research Lab, Materials and Manufacturing Directorate, 3005 Hobson Way, Wright Patterson AFB, Dayton, OH 45433, USA;Department of Physics and Advance Materials Manufacturing Processing Institute, University of North Texas, Denton, TX 76203, USA;Sensor Science Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA;UES, Inc., 4401 Dayton-Xenia Rd, Dayton, OH 45432, USA;

关键词: metamaterials;    homogenization;    magnetic grating;    waveguide coupling;    metasurfaces;   

DOI  :  10.3390/app8040617

来源: DOAJ

【 摘 要 】

Gratings with complex multilayer strips are studied under inclined incident light. Great interest in these gratings is due to applications as input/output tools for waveguides and as subwavelength metafilms. The structured strips introduce anisotropy in the effective parameters, providing additional flexibility in polarization and angular dependences of optical responses. Their characterization is challenging in the intermediate regime between subwavelength and diffractive modes. The transition between modes occurs at the Wood’s anomaly wavelength, which is different at different angle of incidence. The usual characterization with an effective film using permittivity ε and permeabilityμhas limited effectiveness at normal incidence but does not apply at inclined illumination, due to the effect of periodicity. The optical properties are better characterized with effective medium strips instead of an effective medium layer to account for the multilayer strips and the underlying periodic nature of the grating. This approach is convenient for describing such intermediate gratings for two types of applications: both metafilms and the coupling of incident waves to waveguide modes or diffraction orders. The parameters of the effective strips are retrieved by matching the spectral-angular map at different incident angles.

【 授权许可】

Unknown