Controlling enhanced transmission through metallic gratings with subwavelength slits by anisotropic waveguide resonance

We propose an analytically tractable structure for controlling enhanced transmission through a metallic grating with subwavelength slits by filling the slits with an anisotropic material such as a liquid crystal. As the director rotates, the Fabry-Perot condition is modified and the transmission peaks shift. Analytical results of a single-mode theory for the propagation constant, transmission efficiency, and the tunable range of peak wavelengths are given, taking the finite conductivity of metal into account. Analytical results are in good agreement with those calculated by the rigorous coupled-wave analysis, indicating that waveguide resonance plays a dominant role and the results are scalable. (C) 2007 American Institute of Physics.