Band structures of surface acoustic waves in nanostructured phononic crystals with defects

摘要

The band structures of surface acoustic waves in nanostructured phononic crystals with defects have been studied by Brillouin light scattering and finite-element simulations. The crystals are one-dimensional periodic arrays of alternating gold stripes and air gaps on SiO_2/Si substrates, where the periodic defects are gold stripes with non-regular widths. The general features of the band structures are similar to those of the perfect crystal, with the main difference being the appearance of nearly dispersionless defect branches within the bandgap. The defect modes exhibit localization features and are frequency-tunable by varying the defect stripe size.