Influence of vertex angles on the extraordinary optical transmission characteristics of triangular and bow-tie-shaped apertures

The influence of vertex angles on the extraordinary optical transmission (EOT) characteristics of isosceles triangular apertures is numerically investigated with a three-dimensional finite-difference time-domain (FDTD) method. It has been found that the resonant peak characteristics are dependent on the vertex angles of triangular aperture (TA) and the polarized directions of incident light. The resonant peak amplitude is dramatically decreased, when the vertex angle is increased. A blue-shift/red-shift phenomenon is observed in both of the two cases. Detailed studies indicate that the transmission peak characteristics are due to the effects of localized surface plasmon modes excited along the sidewalls and Fabry–Pérot-like resonance. The EOT performance of TA arrays is compared with that of the rectangular aperture arrays. In addition, a bow-tie-shaped aperture (BTA) can be recognized as two overlapped TAs. The EOT properties of BTA with varying bow angles are also studied and analyzed.