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The transmission of higher order surface plasmon (SP) modes can be enhanced through periodic holes array with paired apertures as the basis. The hole shape of the basis pair can be identical circle, square and triangle, etc. It is demonstrated that the concept of structure factor in constructing the reciprocal lattice of a crystal in solid state physics can be adopted to explain the observed intensity of the higher order modes. It is found that the separation between the paired holes is the key factor to determine the strength of the higher order surface plasmon modes. Here we demonstrate this new concept of enhanced higher order SP modes both experimentally and theoretically.

extraordinary transmission; plasmonics; mid-infrared; high order modes