Gap plasmon waveguide with a stub: structure for a wavelengthselective device

摘要

We have performed the three dimensional (3D) numerical analysis for a gap plasmon waveguide with two stubs in a silver film by using the 3D finite-difference time-domain (FDTD) method. The simulated transmittance shows that such the 3D structure works as a wavelength selective device with submicron size as already predicted in the 2D simulations. We have also fabricated such a structure on a glass substrate by using the focused ion beam method. The width of the gap is around 150 nm. The observed transmittance spectra of the structure have clearly indicated the wavelength dependence and agree well with those obtained by a numerical simulation. Our results show that the structure proposed by us is promising for a compact wavelength selective device.