Enhanced and tunable resolution from an imperfect negative refractive index lens

Material loss diminishes the ability of a negative refractive index material to function as a superresolution lens. We find that the transmittance of a negative index slab can be greatly enhanced at a certain evanescent field spatial frequency if the imaginary parts of the permittivity and permeability in the slab can be tuned, even when the object, lens, and image domains have overall loss. This leads to a proposed method to image the far-subwavelength features of an object by reconstructing the evanescent part of its spectrum.