Resonant photon transport through metal-insulator-metal multilayers consisting of Ag and ${\text{SiO}}_2$

We have conducted experimental and numerical studies on resonant photon transport through ${\text{Ag-SiO}}_2\text{-Ag}$ multilayers with varying ${\text{SiO}}_2$ gap-layer thickness due to its application toward the development of a metamaterial superlens. Photon-transport spectra that have been measured using a double-prism system with a $p$-polarized He-Ne laser show a resonant photon tunneling (RPT) peak in the total reflection region and an additional peak in the propagating region. Calculated dispersion curves and electric field profiles reveal that the RPT peak is brought about by antisymmetrically coupled surface-plasmon polaritons (SPPs), very similar to the long-range SPPs in a single-metal film. The additional peak, however, is caused by TM guided modes with symmetrically coupled SPPs. We demonstrate that the ${\text{TM}}_0$ guided modes move continuously from the total reflecting region to the propagating region as the gap-layer thickness decreases. This will enable us to realize a device which converts evanescent waves into propagating waves of light, opening the possibility of an alternative type of hyperlens.

Figure 1

(Color online) (a) The sample structure and (b) far-field transmittance of the samples measured using UV-Vis spectrometer. The dotted-dashed (blue) line, dashed (light blue) line, dotted (purple) line, and solid (red) line correspond to samples for which $d=56\text{nm}$, 140 nm, 420 nm, and 840 nm, respectively.

Figure 2

(Color online) Measured (a) reflection and (b) transport spectra with $p$-polarized light. The dotted-dashed (blue) line, dashed (light blue) line, dotted (purple) line, and solid (red) line correspond to samples for which $d=56\text{nm}$, 140 nm, 420 nm, and 840 nm, respectively.

Figure 3

(Color online) Calculated (a) reflection and (b) transport spectra with $p$-polarized light of $\lambda =633\text{nm}$.

Figure 4

(Color online) Polarization dependence of the measured spectra for (a) $d=420\text{nm}$ and (b) $d=840\text{nm}$. Blue and light blue lines correspond to reflection spectra. Purple and red lines correspond to transport spectra. Solid lines are those obtained with $p$-polarized light. Dotted lines are those obtained with $s$-polarized light.

Figure 5

(Color online) Calculated dispersion curves for $d=56\text{nm}$.

Figure 6

(Color online) Calculated profile of electric field in the multilayer where $d=56\text{nm}$ at ${\theta }_i=62.95°$.

Figure 7

(Color online) Calculated dispersion curves for $d=420\text{nm}$.

Figure 8

(Color online) Calculated profiles of electric field in the multilayer where $d=420\text{nm}$. (a) ${\theta }_i=60.55°$ and (b) ${\theta }_i=57.05°$.

Figure 9

(Color online) Calculated dispersion curves for $d=840\text{nm}$.

Figure 10

(Color online) Calculated profiles of electric field in the multilayer where $d=840\text{nm}$. (a) ${\theta }_i=59.55°$ and (b) ${\theta }_i=51.25°$.