Figure 1

(a) The geometry of an imaging system consisting of a stripe of a MDM structure on a metal surface. The arrows on the metal surface indicate the lens operation. (b) The dispersion relations for modes of a metal-air interface (left panel), and for modes in an MDM structure with $d=0.1{\lambda }_p$ and ${\epsilon }_d=4$ (right panel). The corresponding structures are shown in the inset. The gray areas represent the continuum of extended modes in metal regions. ${\omega }_p$ is the bulk plasma frequency of the metal, and $k_p\equiv {\omega }_p/c$, respectively. The black dots in both figures indicate the frequency ${\omega }_0$ at which the wave vectors of the modes in the two structures match in magnitude. (c) The constant frequency contours at ${\omega }_0$ for both the metal-surface region (left side) and the MDM region (right side). The solid line in the middle represents the boundary of the two regions. The arrows indicate the group velocity directions. The dashed line represents the condition for conservation of wave vectors parallel to the boundary.Reuse & Permissions

Figure 2

The magnetic field profiles for: (a) A mode of the metal-air interface (left panel) and a mode in the second band of a homo-MDM structure (right panel). All metals have the same plasma frequency ${\omega }_p$; the dielectric region has a thickness of $0.1{\lambda }_p$ and a dielectric constant of 4. Both modes have the same frequency $0.62{\omega }_p$ and the same wave number $k_p$. (b) A mode of the metal-air interface (left panel) and a mode in the second band of a hetero-MDM structure (right panel). The metal at the top has a plasma frequency ${\omega }_p^{\prime }=0.6{\omega }_p$. The dielectric region has the thickness of $0.1{\lambda }_p$ and the dielectric constant of 4. Both modes have the same frequency $0.539{\omega }_p$ and the same wave number $0.69k_p$.Reuse & Permissions

Figure 3

The imaging process for surface plasmons with a hetero-MDM lens. The computational set up is schematically shown in Fig. 1. (a) Plotted here is the steady-state $E_x$ field distribution on a cross section at $0.18{\lambda }_p$ above the bottom metal surface. The color scheme is chosen to saturate at large field values in order to show the formed image clearly. (b) The time average $E_x$ field intensity at the image plane for two point sources oscillating in phase. The lens has a length of $1.7{\lambda }_p$. The two point sources are separated by $0.93{\lambda }_p$ apart, and are placed at $0.5{\lambda }_p$ away from the edge of the lens. In comparison, at the operating frequency $\omega =0.539{\omega }_p$, the surface plasmon wave at the metal-air interface has a wavelength of $1.46{\lambda }_p$.Reuse & Permissions

Figure 4

(a) Cross-sectional view of a simulated structure for the purpose of demonstrating imaging process with realistic material parameters. The solid and dashed arrows indicate the positions of the source and the image, respectively. (b) Steady-state $E_x$ field for the structure shown in Fig. 4a, on a cross section at 60 nm above the bottom Ag surface.Reuse & Permissions