Improving the transmittance of the plasmonic slot filter by using a single reflector

A scheme to improve the transmittance of the metal-insulator-metal (MIM) plasmonic slot filter is proposed and numerically studied. Using this scheme, the transmittance of all channels in the MIM slot filter can be significantly improved by using only one reflector. The simulation results show that the transmittance of all channels with this scheme is almost 160% higher than without it. A single-channel filter at 980 nm and a three-channel filter are both demonstrated using this scheme. All the work above is completed by the finite-element analysis method. The model and characteristics of the structure with periodical stubs are also introduced and analyzed. For the first time, to our knowledge, the expressions of all four elements of the transfer matrix together with the reflectance of the periodical stubs are given. It is believed that our research will help to provide new ideas for improving transmittance and promote the application of plasmonic filters.