plasmon resonance of the hollow triangular nanostructures with different holes

In hollow nanostructures, the inner and outer surface plasmons couple together that provides interesting plasmonic properties resulting in the enhancement of the plasmonic field. in addition, triangular structures are interesting for plasmonic applications due to their sharp corners and low symmetry. in this work, gold triangular nanostructures with triangular (ttn) and circular (ctn) holes in their centers have been simulated using the fdtd method and their plasmonic properties have been compared. the extinction spectra of the structures display that ctn has only one plasmonic peak, whereas ttn has several plasmonic modes due to its lower symmetry. each peak presents different interactions between the multipoles that understand from the charge density distribution. also, the figure of merit (fom) of the peaks has been calculated and a high value of 33 is obtained for one of the ttn modes, which is appropriate for sensing application.