The influence of hole shape on enhancing transmission through subwavelength hole arrays

The extraordinary light transmission through a 200-nm thick gold film when passing through different subwavelength hole arrays is observed experimentally. The sample is fabricated by electron beam lithography and reactive ion etching system. A comparison between light transmissions shows that the hole shape changing from rectangular to diamond strongly affects the transmission intensity although both structures possess the same lattice constant of 600 nm. Moreover, the position of the transmission maximum undergoes a spectral red-shift of about 63 nm. Numerical simulations by using a transfer matrix method reproduce the observed transmission spectrum quite well.