Theoretical Study on Interferometric Illumination of Gold Colloid-Sphere Monolayers to Produce Complex Structures for Spectral Engineering

Theoretical study on the interferometric illumination of colloid-sphere monolayers (IICSM) is presented to produce complex plasmonic structures consisting of wavelength-scaled periodic arrays of nano-objects with arbitrary array symmetry and controllable nanoscaled substructure. The IICSM method is based on illumination of hexagonal colloidsphere monolayers by interference patterns synchronized with sphere arrays along arbitrary preselected crystallographic directions. This nanokaleidoscope method enables tuning four structure parameters independently: the symmetry and characteristic periodicity of the interference pattern might be varied by the number, wavelength, and angle of incidence of the interfering beams; the distance between the nano-objects is controllable by the relative orientation of the interference pattern with respect to the hexagonal lattice of colloid spheres; the size of individual nano-objects is determined by the colloid-spheres' diameter and by the light wavelength; and the substructure size-parameter sensitively depends on the polarization state and can be tuned with the nano-object size simultaneously. Finite element method is applied to demonstrate the capabilities of IICSM based on gold colloid spheres and the impact of the resulted complex plasmonic patterns on spectral properties of thin gold films. The possibility of realizing spectral engineering with predesigned rectangular arrays of hole doublets that may be produced uniquely by IICSM is shown.