A proof of superlensing in the quasistatic regime, and limitations of superlenses in this regime due to anomalous localized resonance
Enlarging upon work of Nicorovici, McPhedran & Milton (Nicorovici et al. 1994 Phys. Rev. B49(12), 8479-8482), a rigorous proof is given that in the quasistatic regime a cylindrical superlens can successfully image a dipole line source in the limit as the loss in the lens tends to zero. In this limit it is proved that the field magnitude diverges to infinity in two sometimes overlapping annular anomalously locally resonant regions, one of which extends inside the lens and the other of which extends outside the lens. The wavelength of the oscillations in the locally resonant regimes is set by the geometry and the loss, and goes to zero as the loss goes to zero. If the object or source being imaged responds to an applied field it is argued that it must lie outside the resonant regions to be successfully imaged. If the image is being probed it is argued that the resonant regions created by the probe should not surround the tip of the probe. These conditions taken together make it difficult to directly probe the potential in the near vicinity of the image of a source or object having small extent. The corresponding quasistatic results for the slab lens are also derived. If the source is too close to the slab lens, i.e. lying within the resonant region, then the power dissipation in the lens tends to infinity as the loss goes to zero, which makes the lens impractical for imaging such quasistatic sources. Perfect imaging in a cylindrical superlens is shown to extend to the static equations of magnetoelectricity or thermoelectricity, provided they have a special structure which makes these equations equivalent to the quasistatic equations.