Analysis of surface plasmon polariton conversion coefficient in slit-groove structure

A method for the analysis of finding the conversion efficiency of the surface plasmon polariton in slit-groove structures is proposed and studied. The conversion efficiency of the surface plasmon polariton can be determined by measuring the intensities of light scattered at the slit and groove positions. To verify the usefulness of the proposed method, two rigorous simulations based on the finite-difference time-domain method were executed and the simulation results compared with previously reported data. One was to mimic the far-field imaging experiment in slit-groove structure and the other was to calculate the conversion coefficient directly in a single scattering structure. The SPP conversion efficiencies obtained from the two simulations were approximately 0.232 and 0.220 respectively, and these agreed with the reported data. The suggested method can be used regardless of the shape of the plasmon-generation structure; therefore, it is expected to be useful in a wide range of experiments with different scattering structures.