Apr 20th, 1:00 PM - 4:00 PM
Surface Plasmon Enhanced Optical Transmission through Periodically Modified Metallic Membrane
Dr. Wan Kuang
Surface plasmon-polariton resonance (SPR) is a phenomenon where valence electrons of the metal resonantly interact with incident light. In the case of a sub-wavelength periodically modified metallic membrane, it is shown that an enhanced optical transmission can be achieved. The SPR condition depends on the lattice constant, incident angle, wavelength as well as dielectric constant of the material interfacing the membrane. The presence of a high refractive index chemical on the metal membrane will cause a spectral shift in the transmission peaks. This is the basis for SPR chemical sensing. SPR based chemical sensors offer an improved sensitivity with a small device footprint. This work studied the relationship between the resonant conditions and lattice geometries of the metal membrane. The optical transmittance of a triangular lattice Ag membrane under varying incident angle and polarization has confirmed that the peak optical transmissions experience a spectral shift as a function of the aforementioned factors. The dispersion relation obtained for this membrane shows promising resemblance to what was predicted by an empty lattice approximation of a theoretical construct. The results indicate that the enhanced optical transmission is due to both the traveling surface plasmon-polariton mode on Ag-silica flat interface and the localized cylindrical mode around the nanoholes. Further studies explore the resonant dependence for devices with square lattices.