Metal-Dielectric Composite Holography for Controlling the Propagations of Surface Plasmon Polaritons

Abstract

Controlling the propagations of surface plasmon polaritons (SPPs) is important for many applications. Now, mainly structures for controlling SPPs are etched directly in the metal surface through experimental methods, such as focus ion beam lithography (FIB). In view of mature technology in processing dielectric products, we propose the metal-dielectric composite holography (MDCH) method to design dielectric structures for controlling the propagation of SPPs. The holographic groove structures are designed in dielectric film to control SPP propagation through the surface electromagnetic wave holography (SWH) method. The mutual coherence theory is applied to analyze the influence of the grooves in dielectric film on the phase of propagating SPPs, and the reconstruction condition is obtained. Based on the analysis results, two schemes are proposed to make MDCH structures satisfy the condition: reducing the width of the grooves or filling the grooves with another dielectric. The finite difference time domain (FDTD) method is applied to test the two schemes. Simulation results prove that two schemes are feasible when the width of the groove is smaller than 40 nm or the refractive index of the filling dielectric is limited to a certain range. The investigation verifies that the MDCH method is feasible and the SPP waves can be controlled with high efficiency. Based on the investigation, the mature hologram-fabricated methods and dielectric-processing methods may be used to fabricate structures for controlling SPP waves. The MDCH method may open up the possibility for mass production of plasmonic devices, avoiding the FIB experimental method.