Influence of lattice symmetry and hole shape on the light enhanced transmission through the subwavelength hole arrays

The golden films with various subwavelength hole arrays on the film surface are designed and fabricated on glass substrate by electron beam lithograply (EBL), focused ion beam (FIB), and reactive ion etching (RIE), respectively. The influences of the hole array symmetry and the hole shape on the light-enhanced transmission through the films are observed and simulated. The experimental results show that when the array lattice constant and the hole diameter are the same in the different array structures which are 1 m and 350 nm respectively, the square hole arrays exhibit two transmission peaks at 1170 nm and 1580 nm with the transmissivities of 3% and 6%, respectively, while the hexagonal hole arrays exhibit an enhanced peak of 14% at 1340 nm; when the lattice constant and the duty cycle are the same for different array stucture, the transmission peaks are different for different hole shapes, which are at 763 nm with transmissivity of 12% for rectangular holes and at 703 nm with the one of 9%, respectively. The numerical simulation results by using the transfer matrix method (TMM) are consistent with the observed results.