Polarization-independent extraordinary optical transmission in one-dimensional metallic gratings with broad slits

Extraordinary optical transmission (EOT) is achievable for transverse-magnetic polarization in one-dimensional metallic gratings with very narrow slits due to the excitation of coupled surface plasmon polaritons (SPPs). In contrast, SPP-produced EOT for transverse-electric (TE) polarized light is impossible because of the absence of SPPs for this polarization. However, TE-polarized EOT produced by trapped modes has been demonstrated. In this work, we reanalyze this phenomenon and apply it to gratings with broad slits (still in subwavelength) without the need for a specific dielectric filler in the grooves. The design proposed in this work simplifies and makes more practical the realization of gratings that possess polarization-independent EOT. (C) 2008 American Institute of Physics.