Strong influence of surface structures on enhanced transmission through subwavelength hole arrays

We analyzed the influence of the surface structure on enhanced transmission through subwavelength hole arrays. The hole arrays show extremely large enhanced transmission, but the transmission rapidly decreases as the hole diameter decreases. To clarify the cause of the transmission decrease, we calculated the dimple arrays and found that the diameter of the dimple strongly influences the efficiency of surface plasmon polaritons (SPPs) excitation. We show that the addition of the optimized surface structure to conventional hole arrays for the efficient SPP excitation leads to strongly enhanced transmission in much smaller diameter holes than the incident light wavelength.