Theory of extraordinary optical transmission through subwavelength hole arrays

We present a fully three-dimensional theoretical study of the extraordinary transmission of light through subwavelength hole arrays in optically thick metal films. Good agreement is obtained with experimental data. An analyti cal minimal model is also developed, which conclusively shows that the enha ncement of transmission is due to tunneling through surface plasmons formed on each metal-dielectric interface. Different regimes of tunneling (resona nt through a "surface plasmon molecule," or sequential through two isolated surface plasmons) are found depending on the geometrical parameters defini ng the system.