Achieving frequency red-shift and multiple extraordinary optical transmission via sub-wavelength perfect electrical conductor structure

A novel sub-wavelength perfect electrical conductor (PEC) grating structure was proposed to achieve extraordinary optical transmission (EOT) at far infrared, terahertz and even lower frequency bands. The transmission spectrum of this structure was calculated numerically and compared with that of the conventional metallic grating. It was found that the number of EOT resonance frequencies of the new grating structure increases distinctly and the resonance frequencies red shift significantly. The reason for these improvements in EOT phenomenon was uncovered with the conceptions of optical path length and enhanced effective refractive index.