| In modern optics, many practical applications, particularly the medical ones, would benefit from having image resolution beyond the diffraction limit. This can be achieved by scanning the evanescent fields in the near-field (NSOM) or reducing the effective wavelength with non-linear optical effects (STED). However, all the current subwavelength imaging techniques have their limitations and only appropriate for a small subset of imaging problems. In the last decade researchers have succeeded in demonstrating superlens designs capable of resolution as small as λ/10 by using a thin metal slab, but there is still no physically transparent theory that can interpret all the features of superlens and build a direct connection from design parameters to the image quality.;In this work we investigate the whole superlens imaging process and treat it as an energy distribution process from the emitter in the object space to the detector in the image space via the eigen states of energy. With our novel model we clear the role of each lens parameter and find their optimum values. Our studies also extend the superlens applications to the phase object and show a simulation of clear subwavelength image of phase object. We identify the loss in the metal as the main factor impeding high resolution and discuss two potential methods to improve the quality of image. |
