Fig. 1. (a) The illustration of the superlens formed by an array of width-varied nanoslits perforated in a gold film on a glass substrate. All the nanoslits have the same length l. The width of each nanoslit w is variable. (b) Schematic focusing of the superlens based on the principle of optical interference under the normal illumination of a TE-polarized plane wave. d is the thickness of gold film and f is the focal distance.

Fig. 2. Electric field distributions and Fourier spectra of a metasurface superlense. The FDTD simulated intensity distributions (a) in the y-z plane at x=0, (b) at the focal plane, and (c) in k-space near the superlens focus. The plane z=0 is the exit surface of the superlens. Corresponding theoretically calculated electric field intensity distributions (d) in the y-z plane at x=0, (e) at the focal plane, and (f) in k-space near the superlens focus.

Fig. 3. Experimental demonstration of the quasi-far-field super-resolution focusing superlens. (a) A scanning electron micrograph of the fabricated superlens using FIB. (b) Measured intensity distributions in the y-z plane at x=0. (c) The measured and FDTD simulated intensity distribution at the focal plane.